diff --git a/src/coffee/models/crafting/crafting_plan.coffee b/src/coffee/models/crafting/crafting_plan.coffee
index ca86baa92..1161cb909 100644
--- a/src/coffee/models/crafting/crafting_plan.coffee
+++ b/src/coffee/models/crafting/crafting_plan.coffee
@@ -5,8 +5,82 @@ Copyright (c) 2015 by Redwood Labs
 All rights reserved.
 ###
 
+Inventory = require '../inventory'
+
 ########################################################################################################################
 
 module.exports = class CraftingPlan
 
-    constructor: ->
+    constructor: (steps, wanted)->
+        if not steps? then throw new Error 'steps is required'
+        if not wanted? then throw new Error 'wanted is required'
+
+        @_produced = new Inventory
+        @_required = new Inventory
+        @_steps    = steps
+        @_wanted   = wanted
+
+        @_computeRequired()
+
+    # Property Methods #############################################################################
+
+    Object.defineProperties @prototype,
+        length:
+            get: -> @steps.length
+        produced:
+            get: -> @_produced
+        required:
+            get: -> @_required
+        steps:
+            get: -> @_steps
+        wanted:
+            get: -> @_wanted
+
+    # Object Overrides #############################################################################
+
+    toString: ->
+        return "#{@constructor.name}{
+            wanted:#{@wanted},
+            required:#{@required},
+            steps:[#{(step.toString() for step in @steps).join(',')}],
+            produced:#{@produced}
+            }"
+
+    # Private Methods ##############################################################################
+
+    _computeRequired: ->
+        @_required.addInventory @_wanted
+
+        for i in [@_steps.length-1..0] by -1
+            recipe = @_steps[i]
+
+            for stack in recipe.output
+                while @_required.quantityOf(stack.itemSlug) > 0
+                    @_executeRecipe recipe
+
+        @_produced.addInventory @_wanted
+
+    _executeRecipe: (recipe)->
+        #console.log "executing: #{recipe}"
+        for stack in recipe.input
+            @_use stack
+        for stack in recipe.output
+            @_produce stack
+
+    _produce: (stack)->
+        deficit     = @_required.quantityOf stack.itemSlug
+        replenished = Math.min deficit, stack.quantity
+        surplus     = stack.quantity - replenished
+
+        #console.log "producing #{stack.itemSlug}, surplus: #{surplus}, replenished:#{replenished}"
+        @_produced.add stack.itemSlug, surplus
+        @_required.remove stack.itemSlug, replenished
+
+    _use: (stack)->
+        available = @_produced.quantityOf stack.itemSlug
+        consumed  = Math.min stack.quantity, available
+        deficit   = stack.quantity - consumed
+
+        #console.log "using #{stack.itemSlug}, consumed: #{consumed}, deficit:#{deficit}"
+        @_produced.remove stack.itemSlug, consumed
+        @_required.add stack.itemSlug, deficit
diff --git a/src/coffee/models/crafting/graph_builder.coffee b/src/coffee/models/crafting/graph_builder.coffee
index 4d83efc55..02ef2b822 100644
--- a/src/coffee/models/crafting/graph_builder.coffee
+++ b/src/coffee/models/crafting/graph_builder.coffee
@@ -19,7 +19,6 @@ module.exports = class GraphBuilder
         @_wanted = options.wanted ?= new Inventory
 
         @_wanted.on 'change', => @reset()
-
         @reset()
 
     # Public Methods ###############################################################################
diff --git a/src/coffee/models/crafting/plan_builder.coffee b/src/coffee/models/crafting/plan_builder.coffee
index 63383b9e3..185f2f424 100644
--- a/src/coffee/models/crafting/plan_builder.coffee
+++ b/src/coffee/models/crafting/plan_builder.coffee
@@ -6,14 +6,18 @@ All rights reserved.
 ###
 
 CraftingNode = require './crafting_node'
+CraftingPlan = require './crafting_plan'
+Inventory    = require '../inventory'
 
 ########################################################################################################################
 
 module.exports = class PlanBuilder
 
-    constructor: (rootNode)->
+    constructor: (rootNode, options={})->
         if not rootNode? then throw new Error 'rootNode is required'
 
+        @wanted = options.wanted
+
         @_choiceNodes = []
         @_complete    = false
         @_plans       = []
@@ -26,9 +30,9 @@ module.exports = class PlanBuilder
     producePlans: (maxPlans=null)->
         maxPlans = if maxPlans then @plans.length + maxPlans else Number.MAX_VALUE
 
-        while @plans.length < maxPlans and not @complete
+        while @plans.length is 0 or (@plans.length < maxPlans and not @complete)
             plan = @_captureCurrentPlan()
-            @plans.push plan if plan.length > 0
+            @plans.push plan
             @_incrementChoiceNodes()
 
         return @_plans
@@ -41,15 +45,22 @@ module.exports = class PlanBuilder
     getPlans: ->
         return @_plans
 
+    getWanted: ->
+        return @_wanted
+
+    setWanted: (wanted)->
+        @_wanted = wanted or new Inventory
+
     Object.defineProperties @prototype,
         complete: { get:@prototype.isComplete }
-        plans: { get:@prototype.getPlans }
+        plans:    { get:@prototype.getPlans }
+        wanted:   { get:@prototype.getWanted, set:@prototype.setWanted }
 
     # Private Methods ##############################################################################
 
     _captureCurrentPlan: ->
         toVisit = [@_rootNode]
-        plan = []
+        steps = []
 
         while toVisit.length > 0
             node = toVisit.shift()
@@ -59,10 +70,12 @@ module.exports = class PlanBuilder
             else if node.TYPE is CraftingNode::TYPES.ITEM
                 toVisit.push node.children[0] if node.children.length > 0
             else if node.TYPE is CraftingNode::TYPES.RECIPE
-                plan.push node.recipe
+                steps.push node.recipe
                 toVisit.push(c) for c in node.children
 
-        return plan.reverse()
+        steps.reverse()
+        plan = new CraftingPlan steps, @_wanted
+        return plan
 
     _incrementChoiceNodes: ->
         index = @_choiceNodes.length - 1
diff --git a/src/coffee/models/inventory.coffee b/src/coffee/models/inventory.coffee
index f26184c39..918b5ba8c 100644
--- a/src/coffee/models/inventory.coffee
+++ b/src/coffee/models/inventory.coffee
@@ -30,6 +30,8 @@ module.exports = class Inventory extends BaseModel
     # Public Methods ###############################################################################
 
     add: (itemSlug, quantity=1)->
+        return this unless quantity > 0
+
         @_add itemSlug, quantity
         @trigger Event.add, this, itemSlug, quantity
         @trigger Event.change, this
@@ -102,12 +104,12 @@ module.exports = class Inventory extends BaseModel
         return stack.quantity
 
     remove: (itemSlug, quantity=null)->
-        return if quantity is 0
-
         stack = @_stacks[itemSlug]
-        if not stack? then throw new Error "cannot remove #{itemSlug} since it is not in this inventory"
+        return this unless stack?
 
         quantity ?= stack.quantity
+        return this unless quantity > 0
+
         if stack.quantity < quantity
             throw new Error "cannot remove #{quantity}: only #{stack.quantity} #{itemSlug} in this inventory"
 
@@ -115,7 +117,7 @@ module.exports = class Inventory extends BaseModel
         if stack.quantity is 0
             @stopListening stack
             delete @_stacks[itemSlug]
-            @_itemSlugs = _(@_itemSlugs).without itemSlug
+            @_itemSlugs = (s for s in @_itemSlugs when not ItemSlug.equal(s, itemSlug))
 
         @trigger Event.remove, this, itemSlug, quantity
         @trigger Event.change, this
@@ -164,8 +166,16 @@ module.exports = class Inventory extends BaseModel
     getIsEmpty: ->
         return @_itemSlugs.length is 0
 
+    getTotalQuantity: ->
+        total = 0
+        @each (stack)->
+            total += stack.quantity
+        return total
+
+
     Object.defineProperties @prototype,
-        isEmpty: { get:@prototype.getIsEmpty }
+        isEmpty:       { get:@prototype.getIsEmpty }
+        totalQuantity: { get:@prototype.getTotalQuantity }
 
     # Object Overrides #############################################################################
 
@@ -186,7 +196,7 @@ module.exports = class Inventory extends BaseModel
 
     _add: (itemSlug, quantity=1)->
         return unless itemSlug?
-        return if quantity is 0
+        return unless quantity > 0
 
         stack = @_stacks[itemSlug]
         if not stack?
diff --git a/test/crafting/crafting_plan.test.coffee b/test/crafting/crafting_plan.test.coffee
new file mode 100644
index 000000000..3c729eec1
--- /dev/null
+++ b/test/crafting/crafting_plan.test.coffee
@@ -0,0 +1,49 @@
+###
+Crafting Guide - crafting_plan.test.coffee
+
+Copyright (c) 2015 by Redwood Labs
+All rights reserved.
+###
+
+CraftingPlan = require '../../src/coffee/models/crafting/crafting_plan'
+fixtures     = require './fixtures'
+
+########################################################################################################################
+
+describe 'crafting_plan.coffee', ->
+
+    it 'requires wanted item if gatherable', ->
+        plans = fixtures.makePlans [1, 'test__coal']
+        plans.length.should.equal 1
+
+        plan = plans[0]
+        plan.required.unparse().should.equal 'coal'
+        plan.produced.unparse().should.equal 'coal'
+
+    it 'can compute a single item with a single step', ->
+        plans = fixtures.makePlans [1, 'test__charcoal']
+        plans.length.should.equal 1
+
+        plan = plans[0]
+        plan.required.unparse().should.equal 'coal:8.oak_wood'
+        plan.produced.unparse().should.equal '8.charcoal'
+
+    it 'can compute a large quantity of a single item with a single step', ->
+        plans = fixtures.makePlans [15, 'test__charcoal']
+        plans.length.should.equal 1
+
+        plan = plans[0]
+        plan.required.unparse().should.equal '2.coal:16.oak_wood'
+        plan.produced.unparse().should.equal '16.charcoal'
+
+    it 'can compute a single item with multiple steps', ->
+        plans = fixtures.makePlans [1, 'test__iron_ingot']
+        plans.length.should.equal 2
+
+        plan = plans[0]
+        plan.required.unparse().should.equal 'coal:8.iron_ore:8.oak_wood'
+        plan.produced.unparse().should.equal '7.charcoal:iron_ingot'
+
+        plan = plans[1]
+        plan.required.unparse().should.equal 'coal:8.iron_ore'
+        plan.produced.unparse().should.equal 'iron_ingot'
diff --git a/test/crafting/fixtures.coffee b/test/crafting/fixtures.coffee
index df7d34db5..8093685e3 100644
--- a/test/crafting/fixtures.coffee
+++ b/test/crafting/fixtures.coffee
@@ -10,6 +10,7 @@ ItemSlug     = require '../../src/coffee/models/item_slug'
 Mod          = require '../../src/coffee/models/mod'
 ModPack      = require '../../src/coffee/models/mod_pack'
 ModVersion   = require '../../src/coffee/models/mod_version'
+PlanBuilder  = require '../../src/coffee/models/crafting/plan_builder'
 
 ########################################################################################################################
 
@@ -21,6 +22,7 @@ MOD_VERSION_FILE =
         recipe:
             input: 8 Oak Wood, Coal
             pattern: .0. ... .1.
+            quantity: 8
 
     item: Crafting Table
         recipe:
@@ -100,6 +102,9 @@ MOD_VERSION_FILE =
 
 module.exports = fixtures =
 
+    makeGraphBuilder: ->
+        return new GraphBuilder modPack:fixtures.makeModPack()
+
     makeModPack: ->
         modPack = new ModPack
 
@@ -112,10 +117,18 @@ module.exports = fixtures =
 
         return modPack
 
-    makeGraphBuilder: ->
-        return new GraphBuilder modPack:fixtures.makeModPack()
+    makePlans: (stacks...)->
+        modPack = fixtures.makeModPack()
 
-    makeTree: (itemSlug)->
+        graphBuilder = fixtures.makeGraphBuilder()
+        for stack in stacks
+            graphBuilder.wanted.add ItemSlug.slugify(stack[1]), stack[0]
+        graphBuilder.expandGraph()
+
+        planBuilder = new PlanBuilder graphBuilder.rootNode, wanted:graphBuilder.wanted
+        return planBuilder.producePlans()
+
+    makeTree: (itemSlug, quantity=1)->
         builder = fixtures.makeGraphBuilder()
         builder.wanted.add ItemSlug.slugify itemSlug
         builder.expandGraph()
diff --git a/test/crafting/plan_builder.test.coffee b/test/crafting/plan_builder.test.coffee
index fe1d09a67..8d3aca511 100644
--- a/test/crafting/plan_builder.test.coffee
+++ b/test/crafting/plan_builder.test.coffee
@@ -13,13 +13,14 @@ PlanBuilder = require '../../src/coffee/models/crafting/plan_builder'
 describe 'plan_builder.coffee', ->
 
     printPlan = (plan)->
-        return ((s.slug.replace(/^.*>.*>/, '') for s in plan)).join ' > '
+        return ((s.slug.replace(/^.*>.*>/, '') for s in plan.steps;;)).join ' > '
 
-    it 'generates no plans for a gatherable item', ->
+    it 'generates an empty plan for a gatherable item', ->
         builder = new PlanBuilder fixtures.makeTree 'test__oak_wood'
         plans = builder.producePlans 100
 
-        plans.length.should.equal 0
+        plans.length.should.equal 1
+        plans[0].length.should.equal 0
         builder.complete.should.be.true
 
     it 'can find a multi-step plan', ->
@@ -34,5 +35,5 @@ describe 'plan_builder.coffee', ->
         builder = new PlanBuilder fixtures.makeTree 'test__iron_ingot'
         plans = builder.producePlans 100
 
-        printPlan(plans[0]).should.equal 'test__charcoal > test__iron_ingot'
+        printPlan(plans[0]).should.equal '8 test__charcoal > test__iron_ingot'
         printPlan(plans[1]).should.equal 'test__iron_ingot'
diff --git a/test/crafting_plan.test.coffee b/test/crafting_plan.test.coffee
deleted file mode 100644
index 32e955332..000000000
--- a/test/crafting_plan.test.coffee
+++ /dev/null
@@ -1,84 +0,0 @@
-###
-Crafting Guide - crafting_plan.test.coffee
-
-Copyright (c) 2014-2015 by Redwood Labs
-All rights reserved.
-###
-
-CraftingPlan = require '../src/coffee/models/crafting_plan'
-ItemSlug     = require '../src/coffee/models/item_slug'
-Mod          = require '../src/coffee/models/mod'
-ModPack      = require '../src/coffee/models/mod_pack'
-ModVersion   = require '../src/coffee/models/mod_version'
-
-########################################################################################################################
-
-modPack = plan = null
-
-########################################################################################################################
-
-describe 'crafting_plan.coffee', ->
-
-    beforeEach ->
-        mod = new Mod name:'Minecraft', slug:'minecraft'
-        mod.addModVersion new ModVersion modSlug:mod.slug, version:'1.7.10'
-        mod.activeModVersion.parse """
-            schema:1
-
-            item:Oak Plank;      recipe:; input:Oak Log;                pattern:... .0. ...; quantity:4
-            item:Stick;          recipe:; input:Oak Plank;              pattern:... .0. .0.; quantity:4
-            item:Crafting Table; recipe:; input:Oak Plank;              pattern:00. 00. ...
-            item:Furnace;        recipe:; input:Cobblestone;            pattern:000 0.0 000; tools:Crafting Table
-            item:Iron Ingot;     recipe:; input:Iron Ore, furnace fuel; pattern:.0. ... .1.; tools:Furnace
-            item:Iron Sword;     recipe:; input:Iron Ingot, Stick;      pattern:.0. .0. .1.; tools:Crafting Table
-        """
-        modPack = new ModPack
-        modPack.addMod mod
-
-        plan = new CraftingPlan modPack:modPack, includingTools:false
-
-    describe 'craft', ->
-
-        describe 'under the simplest conditions', ->
-
-            it 'can craft a single step recipe', ->
-                plan.want.add ItemSlug.slugify 'oak_plank'
-                plan.craft()
-                plan.need.unparse().should.equal 'oak_log'
-                plan.result.unparse().should.equal '4.oak_plank'
-
-            it 'can craft a multi-step recipe', ->
-                plan.want.add ItemSlug.slugify 'crafting_table'
-                plan.craft()
-                plan.need.unparse().should.equal 'oak_log'
-                plan.result.unparse().should.equal 'crafting_table'
-
-            it 'can craft a multi-step recipe using tools', ->
-                plan.want.add ItemSlug.slugify 'furnace'
-                plan.craft()
-                plan.need.unparse().should.equal '8.cobblestone'
-                plan.result.unparse().should.equal 'furnace'
-
-            it 'can craft a multi-step recipe re-using tools', ->
-                plan.want.add ItemSlug.slugify 'iron_sword'
-                plan.craft()
-                plan.need.unparse().should.equal '2.furnace_fuel:2.iron_ore:oak_log'
-                plan.result.unparse().should.equal 'iron_sword:2.oak_plank:3.stick'
-
-        describe 'with building tools', ->
-
-            it 'can craft a multi-step recipe using tools', ->
-                plan.includingTools = true
-                plan.want.add ItemSlug.slugify 'furnace'
-                plan.craft()
-                plan.need.unparse().should.equal '8.cobblestone:oak_log'
-                plan.result.unparse().should.equal 'crafting_table:furnace'
-
-            it 'can craft a multi-step recipe re-using tools', ->
-                plan.includingTools = true
-                plan.want.add ItemSlug.slugify 'iron_sword'
-                plan.craft()
-
-                plan.need.unparse().should.eql '8.cobblestone:2.furnace_fuel:2.iron_ore:2.oak_log'
-                plan.result.unparse().should.equal 'crafting_table:furnace:' +
-                    'iron_sword:2.oak_plank:3.stick'
diff --git a/test/inventory.test.coffee b/test/inventory.test.coffee
index 2bef270b6..d699d1184 100644
--- a/test/inventory.test.coffee
+++ b/test/inventory.test.coffee
@@ -189,9 +189,12 @@ describe 'inventory.coffee', ->
 
     describe 'remove', ->
 
-        it 'throws when the item is absent', ->
-            expect(-> inventory.remove('chicken')).to.throw Error,
-                'cannot remove chicken since it is not in this inventory'
+        it 'does nothing when the item is absent', ->
+            before = inventory.unparse()
+            inventory.remove 'foo'
+            after = inventory.unparse()
+
+            before.should.equal after
 
         it 'throws when the item has insufficient quantity', ->
             expect(-> inventory.remove('wool', 10)).to.throw Error,