diff --git a/build.js b/build.js
index af00975..e9c54b1 100644
--- a/build.js
+++ b/build.js
@@ -44,19 +44,109 @@ function levelToHPBase(level){
     }
 }
 
+/**
+ * @description Error to catch items that don't exist.
+ * @module ItemNotFound
+ */
+class ItemNotFound {
+    /**
+     * @class
+     * @param {String} item the item name entered
+     * @param {String} type the type of item
+     * @param {Boolean} genElement whether to generate an element from inputs
+     * @param {String} override override for item type
+     */
+    constructor(item, type, genElement, override) {
+        /** 
+         * @public 
+         * @type {String}
+         */
+        this.message = `Cannot find ${override||type} named ${item}`;
+        if (genElement)
+            /** 
+             * @public 
+             * @type {Element}
+             */
+            this.element = document.getElementById(`${type}-choice`).parentElement.querySelectorAll("p.error")[0];
+        else
+            this.element = document.createElement("div");
+    }
+}
+
+/**
+ * @description Error to catch incorrect input.
+ * @module IncorrectInput 
+ */
+class IncorrectInput {
+    /**
+     * @class
+     * @param {String} input the inputted text
+     * @param {String} format the correct format
+     * @param {String} sibling the id of the error node's sibling
+     */
+    constructor(input, format, sibling) {
+        /** 
+         * @public
+         * @type {String}
+         */
+        this.message = `${input} is incorrect. Example: ${format}`;
+        /**
+         * @public
+         * @type {String}
+         */
+        this.id = sibling;
+    }
+}
+
+/**
+ * @description Error that inputs an array of items to generate errors of.
+ * @module ListError
+ * @extends Error
+ */
+class ListError extends Error {
+    /**
+     * @class
+     * @param {Array} errors array of errors
+     */
+    constructor(errors) {
+        let ret = [];
+        if (typeof errors[0] == "string") {
+            super(errors[0]);
+        } else {
+            super(errors[0].message);
+        }
+        for (let i of errors) {
+            if (typeof i == "string") {
+                ret.push(new Error(i));
+            } else {
+                ret.push(i);
+            }
+        }
+        /**
+         * @public
+         * @type {Object[]}
+         */
+        this.errors = ret;
+    }
+}
+
 /*Class that represents a wynn player's build.
 */
 class Build{
     
-    /*
-     * Construct a build.
-     * @param level : Level of the player.
-     * @param equipment : List of equipment names that make up the build.
+    /**
+     * @description Construct a build.
+     * @param {Number} level : Level of the player.
+     * @param {String[]} equipment : List of equipment names that make up the build.
      *                    In order: Helmet, Chestplate, Leggings, Boots, Ring1, Ring2, Brace, Neck, Weapon.
-     * @param powders : Powder application. List of lists of integers (powder IDs).
+     * @param {Number[]} powders : Powder application. List of lists of integers (powder IDs).
      *                  In order: Helmet, Chestplate, Leggings, Boots, Weapon.
+     * @param {Object[]} inputerrors : List of instances of error-like classes.
      */
-    constructor(level,equipment, powders, externalStats){
+    constructor(level,equipment, powders, externalStats, inputerrors=[]){
+
+        let errors = inputerrors;
+
         // NOTE: powders is just an array of arrays of powder IDs. Not powder objects.
         this.powders = powders;
         if(itemMap.get(equipment[0]) && itemMap.get(equipment[0]).type === "helmet") {
@@ -64,67 +154,99 @@ class Build{
             this.powders[0] = this.powders[0].slice(0,helmet.slots); 
             this.helmet = expandItem(helmet, this.powders[0]);
         }else{
-            throw new TypeError("No such helmet named "+ equipment[0]);
+            const helmet = itemMap.get("No Helmet");
+            this.powders[0] = this.powders[0].slice(0,helmet.slots);
+            this.helmet = expandItem(helmet, this.powders[0]);
+            errors.push(new ItemNotFound(equipment[0], "helmet", true));
         }
         if(itemMap.get(equipment[1]) && itemMap.get(equipment[1]).type === "chestplate") {
             const chestplate = itemMap.get(equipment[1]);
             this.powders[1] = this.powders[1].slice(0,chestplate.slots); 
             this.chestplate = expandItem(chestplate, this.powders[1]);
         }else{
-            throw new TypeError("No such chestplate named "+ equipment[1]);
+            const chestplate = itemMap.get("No Chestplate");
+            this.powders[1] = this.powders[1].slice(0,chestplate.slots); 
+            this.chestplate = expandItem(chestplate, this.powders[1]);
+            errors.push(new ItemNotFound(equipment[1], "chestplate", true));
         }
         if(itemMap.get(equipment[2]) && itemMap.get(equipment[2]).type === "leggings") {
             const leggings = itemMap.get(equipment[2]);
             this.powders[2] = this.powders[2].slice(0,leggings.slots); 
             this.leggings = expandItem(leggings, this.powders[2]);
         }else{
-            throw new TypeError("No such leggings named "+ equipment[2]);
+            const chestplate = itemMap.get("No Leggings");
+            this.powders[1] = this.powders[1].slice(0,chestplate.slots); 
+            this.chestplate = expandItem(chestplate, this.powders[1]);
+            errors.push(new ItemNotFound(equipment[2], "leggings", true));
         }
         if(itemMap.get(equipment[3]) && itemMap.get(equipment[3]).type === "boots") {
             const boots = itemMap.get(equipment[3]);
             this.powders[3] = this.powders[3].slice(0,boots.slots); 
             this.boots = expandItem(boots, this.powders[3]);
         }else{
-            throw new TypeError("No such boots named "+ equipment[3]);
+            const boots = itemMap.get("No Boots");
+            this.powders[3] = this.powders[3].slice(0,boots.slots); 
+            this.boots = expandItem(boots, this.powders[3]);
+            errors.push(new ItemNotFound(equipment[3], "boots", true));
         }
         if(itemMap.get(equipment[4]) && itemMap.get(equipment[4]).type === "ring") {
             const ring = itemMap.get(equipment[4]);
             this.ring1 = expandItem(ring, []);
         }else{
-            throw new TypeError("No such ring named "+ equipment[4]);
+            const ring = itemMap.get("No Ring 1");
+            this.ring1 = expandItem(ring, []);
+            errors.push(new ItemNotFound(equipment[4], "ring1", true, "ring"));
         }
         if(itemMap.get(equipment[5]) && itemMap.get(equipment[5]).type === "ring") {
             const ring = itemMap.get(equipment[5]);
             this.ring2 = expandItem(ring, []);
         }else{
-            throw new TypeError("No such ring named "+ equipment[5]);
+            const ring = itemMap.get("No Ring 2");
+            this.ring2 = expandItem(ring, []);
+            errors.push(new ItemNotFound(equipment[5], "ring2", true, "ring"));
         }
         if(itemMap.get(equipment[6]) && itemMap.get(equipment[6]).type === "bracelet") {
             const bracelet = itemMap.get(equipment[6]);
             this.bracelet = expandItem(bracelet, []);
         }else{
-            throw new TypeError("No such bracelet named "+ equipment[6]);
+            const bracelet = itemMap.get("No Bracelet");
+            this.bracelet = expandItem(bracelet, []);
+            errors.push(new ItemNotFound(equipment[6], "bracelet", true));
         }
         if(itemMap.get(equipment[7]) && itemMap.get(equipment[7]).type === "necklace") {
             const necklace = itemMap.get(equipment[7]);
             this.necklace = expandItem(necklace, []);
         }else{
-            throw new TypeError("No such necklace named "+ equipment[7]);
+            const necklace = itemMap.get("No Necklace");
+            this.necklace = expandItem(necklace, []);
+            errors.push(new ItemNotFound(equipment[7], "necklace", true));
         }
         if(itemMap.get(equipment[8]) && itemMap.get(equipment[8]).category === "weapon") {
             const weapon = itemMap.get(equipment[8]);
             this.powders[4] = this.powders[4].slice(0,weapon.slots); 
             this.weapon = expandItem(weapon, this.powders[4]);
         }else{
-            throw new TypeError("No such weapon named "+ equipment[8]);
+            const weapon = itemMap.get("No Weapon");
+            this.powders[4] = this.powders[4].slice(0,weapon.slots); 
+            this.weapon = expandItem(weapon, this.powders[4]);
+            errors.push(new ItemNotFound(equipment[8], "weapon", true));
         }
-        if(level < 1){ //Should these be constants?
+
+        if (level < 1) { //Should these be constants?
             this.level = 1;
-        }else if (level > 106){
+        } else if (level > 106) {
             this.level = 106;
-        }else{
+        } else if (level <= 106 && level >= 1) {
             this.level = level;
+        } else if (typeof level === "string") {
+            this.level = level;
+            errors.push(new IncorrectInput(level, "a number", "level-choice"));
+        } else {
+            errors.push("Level is not a string or number.");
         }
+        document.getElementById("level-choice").value = this.level;
+        this.level = 106;
+
         this.availableSkillpoints = levelToSkillPoints(this.level);
         this.equipment = [ this.helmet, this.chestplate, this.leggings, this.boots, this.ring1, this.ring2, this.bracelet, this.necklace ];
         this.items = this.equipment.concat([this.weapon]);
@@ -144,6 +266,13 @@ class Build{
         this.externalStats = externalStats;
 
         this.initBuildStats();
+
+        // Remove every error before adding specific ones
+        for (let i of document.getElementsByClassName("error")) {
+            i.textContent = "";
+        }
+        this.errors = errors;
+        if (errors.length > 0) this.errored = true;
     }  
 
     /*Returns build in string format
diff --git a/builder.js b/builder.js
index e21def8..2d2155c 100644
--- a/builder.js
+++ b/builder.js
@@ -427,29 +427,36 @@ function calculateBuild(save_skp, skp){
             equipment[i] = equip;
         }
         let powderings = [];
+        let errors = [];
         for (const i in powderInputs) {
             // read in two characters at a time.
             // TODO: make this more robust.
             let input = getValue(powderInputs[i]);
             let powdering = [];
+            let errorederrors = [];
             while (input) {
                 let first = input.slice(0, 2);
                 let powder = powderIDs.get(first);
                 console.log(powder);
                 if (powder === undefined) {
-                    throw new TypeError("Invalid powder " + powder + " in slot " + i);
+                    errorederrors.push(first);
+                } else {
+                    powdering.push(powder);
                 }
-                powdering.push(powder);
                 input = input.slice(2);
             }
+            if (errorederrors.length > 0) {
+                if (errorederrors.length > 1)
+                    errors.push(new IncorrectInput(errorederrors.join(""), "t6w6", powderInputs[i]));
+                else
+                    errors.push(new IncorrectInput(errorederrors[0], "t6 or e3", powderInputs[i]));
+            }
+            console.log("POWDERING" + powdering);
             powderings.push(powdering);
         }
-        //level setting
-        let level = document.getElementById("level-choice").value;
-        if(level === ""){
-            level = 106;
-        }
-        document.getElementById("level-choice").value = level;
+        
+        console.log(equipment);
+        player_build = new Build(document.getElementById("level-choice").value, equipment, powderings, new Map(), errors);
 
         for (let i of document.getElementsByClassName("hide-container-block")) {
 			i.style.display = "block";
@@ -458,8 +465,7 @@ function calculateBuild(save_skp, skp){
 			i.style.display = "grid";
 		}
 
-        player_build = new Build(level, equipment, powderings, new Map());
-        //console.log(player_build.toString());
+        console.log(player_build.toString());
         displayEquipOrder(document.getElementById("build-order"),player_build.equip_order);
 
         
@@ -486,21 +492,50 @@ function calculateBuild(save_skp, skp){
         
         calculateBuildStats();
         setTitle();
+        if (player_build.errored)
+            throw new ListError(player_build.errors);
+
     }
     catch (error) {
-        let msg = error.stack;
-        let lines = msg.split("\n");
-        let header = document.getElementById("header");
-        header.textContent = "";
-        for (const line of lines) {
-            let p = document.createElement("p");
-            p.classList.add("itemp");
-            p.textContent = line;
-            header.appendChild(p);
+        if (error instanceof ListError) {
+            for (let i of error.errors) {
+                if (i instanceof ItemNotFound) {
+                    i.element.textContent = i.message;
+                } else if (i instanceof IncorrectInput) {
+                    if (document.getElementById(i.id) !== null) {
+                        document.getElementById(i.id).parentElement.querySelectorAll("p.error")[0].textContent = i.message;
+                    }
+                } else {
+                    let msg = i.stack;
+                    let lines = msg.split("\n");
+                    let header = document.getElementById("header");
+                    header.textContent = "";
+                    for (const line of lines) {
+                        let p = document.createElement("p");
+                        p.classList.add("itemp");
+                        p.textContent = line;
+                        header.appendChild(p);
+                    }
+                    let p2 = document.createElement("p");
+                    p2.textContent = "If you believe this is an error, contact hppeng on forums or discord.";
+                    header.appendChild(p2);
+                }
+            }
+        } else {
+            let msg = error.stack;
+            let lines = msg.split("\n");
+            let header = document.getElementById("header");
+            header.textContent = "";
+            for (const line of lines) {
+                let p = document.createElement("p");
+                p.classList.add("itemp");
+                p.textContent = line;
+                header.appendChild(p);
+            }
+            let p2 = document.createElement("p");
+            p2.textContent = "If you believe this is an error, contact hppeng on forums or discord.";
+            header.appendChild(p2);
         }
-        let p2 = document.createElement("p");
-        p2.textContent = "If you believe this is an error, contact hppeng on forums or discord.";
-        header.appendChild(p2);
     }
 }
 
diff --git a/index.html b/index.html
index fbd1987..7fd5984 100644
--- a/index.html
+++ b/index.html
@@ -34,10 +34,12 @@
                                 <input class="iteminput" list="helmet-items" id="helmet-choice" name="helmet-choice" placeholder="No Helmet"/>
                                 <datalist id="helmet-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                             <td class="left">
                                 <label id="helmet-slots" for="helmet-powder">X slots</label>
                                 <input class="iteminput" type="text" id="helmet-powder" name="helmet-powder" placeholder="Example: t6t6"/>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -46,10 +48,12 @@
                                 <input class="iteminput" list="chestplate-items" id="chestplate-choice" name="chestplate-choice" placeholder="No Chestplate" />
                                 <datalist id="chestplate-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                             <td class="left">
                                 <label id="chestplate-slots" for="chestplate-powder">X slots</label>
                                 <input class="iteminput" type="text" id="chestplate-powder" name="chestplate-powder" />
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -58,10 +62,12 @@
                                 <input class="iteminput" list="leggings-items" id="leggings-choice" name="leggings-choice" placeholder="No Leggings" />
                                 <datalist id="leggings-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                             <td class="left">
                                 <label id="leggings-slots" for="leggings-powder">X slots</label>
                                 <input class="iteminput" type="text" id="leggings-powder" name="leggings-powder" />
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -70,10 +76,12 @@
                                 <input class="iteminput" list="boots-items" id="boots-choice" name="boots-choice" placeholder="No Boots" />
                                 <datalist id="boots-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                             <td class="left">
                                 <label id="boots-slots" for="boots-powder">X slots</label>
                                 <input class="iteminput" type="text" id="boots-powder" name="boots-powder" />
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -83,11 +91,13 @@
                                 <input class="iteminput" list="weapon-items" id="weapon-choice" name="weapon-choice" placeholder="No Weapon" value=""/>
                                 <datalist id="weapon-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                             <td class="left">
                                 <br>
                                 <label id="weapon-slots" for="weapon-powder">X slots</label>
                                 <input class="iteminput" type="text" id="weapon-powder" name="weapon-powder" />
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                     </table>
@@ -105,6 +115,7 @@
                                 <input class="iteminput" list="ring1-items" id="ring1-choice" name="ring1-choice" placeholder="No Ring 1"/>
                                 <datalist id="ring1-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -113,6 +124,7 @@
                                 <input class="iteminput" list="ring2-items" id="ring2-choice" name="ring2-choice" placeholder="No Ring 2" />
                                 <datalist id="ring2-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -121,6 +133,7 @@
                                 <input class="iteminput" list="bracelet-items" id="bracelet-choice" name="bracelet-choice" placeholder="No Bracelet" />
                                 <datalist id="bracelet-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -129,6 +142,7 @@
                                 <input class="iteminput" list="necklace-items" id="necklace-choice" name="necklace-choice" placeholder="No Necklace"/>
                                 <datalist id="necklace-items">
                                 </datalist>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif; white-space: nowrap;"></p>
                             </td>
                         </tr>
                         <tr>
@@ -136,6 +150,7 @@
                                 <br/>
                                 <label for="level-choice">Level:</label>
                                 <input class="iteminput" id="level-choice" name="level-choice" placeholder="106" value=""/>
+                                <p class="error" style="color: red; top: 30px; font-size: 10px; padding: 0; margin: 0; height: 5px; font-family: 'Nunito', sans-serif;"></p>
                             </td>
                         </tr>
                     </table>