diff --git a/lib/squib/api/shapes.rb b/lib/squib/api/shapes.rb
index 4c2d45b..cbdca9b 100644
--- a/lib/squib/api/shapes.rb
+++ b/lib/squib/api/shapes.rb
@@ -1,3 +1,6 @@
+require 'squib/args/box'
+require 'squib/args/draw'
+
 module Squib
   class Deck
 
@@ -23,13 +26,12 @@ module Squib
     # @return [nil] intended to be void
     # @api public
     def rect(opts = {})
-      opts = needs(opts, [:range, :x, :y, :width, :height, :rect_radius, :x_radius, :y_radius,
+      opts = needs(opts, [:range, :rect_radius, :x_radius, :y_radius,
                           :fill_color, :stroke_color, :stroke_width, :layout])
+      box  = Args::Box.new(self).load!(opts, expand_by: size, layout: layout, dpi: dpi)
+      draw = Args::Draw.new.load!(opts, expand_by: size, layout: layout, dpi: dpi)
       opts[:range].each do |i|
-        @cards[i].rect(opts[:x][i], opts[:y][i], opts[:width][i], opts[:height][i],
-                       opts[:x_radius][i], opts[:y_radius][i],
-                       opts[:fill_color][i], opts[:stroke_color][i],
-                       opts[:stroke_width][i])
+        @cards[i].rect(box[i], draw[i])
       end
     end
 
diff --git a/lib/squib/args/arg_loader.rb b/lib/squib/args/arg_loader.rb
new file mode 100644
index 0000000..9954f5f
--- /dev/null
+++ b/lib/squib/args/arg_loader.rb
@@ -0,0 +1,135 @@
+require 'squib/constants'
+require 'squib/conf'
+
+module Squib
+  # @api private
+  module Args
+
+    # Intended to be used a a mix-in,
+    # For example use see Box as an example
+    module ArgLoader
+
+      # Main class invoked by the client (i.e. api/ methods)
+      def load!(args, expand_by: 1, layout: {}, dpi: 300)
+        set_attributes(args: args)
+        expand(by: expand_by)
+        layout_args = prep_layout_args(args[:layout], expand_by: expand_by)
+        defaultify(layout_args: layout_args || [], layout: layout)
+        validate
+        convert_units
+        self
+      end
+
+      # Iterate over the args hash and create instance-level attributes for
+      # each parameter
+      # Assumes we have a hash of parameters to their default keys in the class
+      def set_attributes(args: args)
+        attributes = self.class.parameters.keys
+        attributes.each do |p|
+          instance_variable_set "@#{p}", args[p] # often nil, but ok
+        end
+        self.class.class_eval { attr_reader *(attributes) }
+      end
+
+       # Conduct singleton expansion
+       # If expanding-parameter is not already responding to
+       # :each then copy it into an array
+       #
+       # Assumes we have an self.expanding_parameters
+      def expand(by: 1)
+        exp_params = self.class.expanding_parameters
+        exp_params.each do |p|
+          attribute = "@#{p}"
+          arg = instance_variable_get(attribute)
+          unless arg.respond_to? :each
+            instance_variable_set attribute, [arg] * by #expand singleton
+          end
+        end
+      end
+
+      # Do singleton expansion on the layout argument as well
+      # Treated differently since layout is not always specified
+      def prep_layout_args(layout_args, expand_by: 1)
+        unless layout_args.respond_to?(:each)
+          layout_args = [layout_args] * expand_by
+        end
+        layout_args || []
+      end
+
+      # Go over each argument and fill it in with layout and defaults wherever nil
+      def defaultify(layout_args: [], layout: {})
+        self.class.parameters.each do |param, default|
+          attribute = "@#{param}"
+          val = instance_variable_get(attribute)
+          if val.respond_to? :each
+            new_val = val.map.with_index do |v, i|
+              v ||= layout[layout_args[i]][param] unless layout_args[i].nil?
+              v ||= default
+            end
+            instance_variable_set(attribute, new_val)
+          else # a non-expanded singleton
+            # TODO handle this case
+          end
+        end
+      end
+
+      # For each parameter/attribute foo we try to invoke a validate_foo
+      def validate
+        self.class.parameters.each do |param, default|
+          method    = "validate_#{param}"
+          if self.respond_to? method
+            attribute = "@#{param}"
+            val = instance_variable_get(attribute)
+            if val.respond_to? :each
+              new_val =  val.map.with_index{ |v, i| send(method, v, i) }
+              instance_variable_set(attribute, new_val)
+            else
+              instance_variable_set(attribute,send(method, val))
+            end
+          end
+        end
+      end
+
+      # Access an individual arg for a given card
+      # @return an OpenStruct that looks just like the mixed-in class
+      # @api private
+      def [](i)
+        card_arg = OpenStruct.new
+        self.class.expanding_parameters.each do |p|
+          p_val = instance_variable_get("@#{p}")
+          card_arg[p] = p_val[i]
+        end
+        card_arg
+      end
+
+      # Convert units
+      def convert_units(dpi: 300)
+        self.class.params_with_units.each do |p|
+          p_str = "@#{p}"
+          p_val = instance_variable_get(p_str)
+          if p_val.respond_to? :each
+            arr = p_val.map { |x| convert_unit(x, dpi) }
+            instance_variable_set p_str, arr
+          else
+            instance_variable_set p_str, convert_unit(p_val, dpi)
+          end
+        end
+        self
+      end
+
+      def convert_unit(arg, dpi)
+        case arg.to_s.rstrip
+        when /in$/ #ends with "in"
+          arg.rstrip[0..-2].to_f * dpi
+        when /cm$/ #ends with "cm"
+          arg.rstrip[0..-2].to_f * dpi * INCHES_IN_CM
+        else
+          arg
+        end
+      end
+      module_function :convert_unit
+
+    end
+
+  end
+end
\ No newline at end of file
diff --git a/lib/squib/args/box.rb b/lib/squib/args/box.rb
new file mode 100644
index 0000000..8402dbe
--- /dev/null
+++ b/lib/squib/args/box.rb
@@ -0,0 +1,54 @@
+require 'squib/args/arg_loader'
+
+module Squib
+  # @api private
+  module Args
+
+    class Box
+      include ArgLoader
+
+      def initialize(deck = nil)
+        @deck = deck
+      end
+
+      def self.parameters
+        { x: 0, y: 0,
+          width: :native, height: :native,
+          radius: nil, x_radius: 0, y_radius: 0
+        }
+      end
+
+      def self.expanding_parameters
+        parameters.keys # all of them
+      end
+
+      def self.params_with_units
+        parameters.keys # all of them
+      end
+
+      def validate_width(arg, _i)
+        return arg if @deck.nil?
+        return @deck.width if arg == :native
+        arg
+      end
+
+      def validate_height(arg, _i)
+        return arg if @deck.nil?
+        return @deck.height if arg == :native
+        arg
+      end
+
+      def validate_x_radius(arg, i)
+        return radius[i] unless radius[i].nil?
+        arg
+      end
+
+      def validate_y_radius(arg, i)
+        return radius[i] unless radius[i].nil?
+        arg
+      end
+
+    end
+
+  end
+end
\ No newline at end of file
diff --git a/lib/squib/args/draw.rb b/lib/squib/args/draw.rb
new file mode 100644
index 0000000..3d48cae
--- /dev/null
+++ b/lib/squib/args/draw.rb
@@ -0,0 +1,25 @@
+require 'squib/args/arg_loader'
+
+module Squib
+  # @api private
+  module Args
+
+    class Draw
+      include ArgLoader
+
+      def self.parameters
+        { fill_color: '#0000', stroke_color: :black, stroke_width: 2.0 }
+      end
+
+      def self.expanding_parameters
+        parameters.keys # all of them are expandable
+      end
+
+      def self.params_with_units
+        [:stroke_width]
+      end
+
+    end
+
+  end
+end
\ No newline at end of file
diff --git a/lib/squib/deck.rb b/lib/squib/deck.rb
index 926d659..76c1bf9 100644
--- a/lib/squib/deck.rb
+++ b/lib/squib/deck.rb
@@ -35,7 +35,11 @@ module Squib
                           :img_dir, :prefix, :text_hint, :typographer
     # :nodoc:
     # @api private
-    attr_reader :layout, :conf
+    attr_reader :layout, :conf, :dpi
+
+    #
+    # deck.size is really just @cards.size
+    def_delegators :cards, :size
 
     # Squib's constructor that sets the immutable properties.
     #
diff --git a/lib/squib/graphics/shapes.rb b/lib/squib/graphics/shapes.rb
index 2ab485b..26f4373 100644
--- a/lib/squib/graphics/shapes.rb
+++ b/lib/squib/graphics/shapes.rb
@@ -4,12 +4,10 @@ module Squib
 
     # :nodoc:
     # @api private
-    def rect(x, y, width, height, x_radius, y_radius, fill_color, stroke_color, stroke_width)
-      width  = @width   if width == :native
-      height = @height  if height == :native
+    def rect(box, draw)
       use_cairo do |cc|
-        cc.rounded_rectangle(x, y, width, height, x_radius, y_radius)
-        cc.fill_n_stroke(fill_color, stroke_color, stroke_width)
+        cc.rounded_rectangle(box.x, box.y, box.width, box.height, box.x_radius, box.y_radius)
+        cc.fill_n_stroke(draw.fill_color, draw.stroke_color, draw.stroke_width)
       end
     end
 
diff --git a/spec/args/box_spec.rb b/spec/args/box_spec.rb
new file mode 100644
index 0000000..5388185
--- /dev/null
+++ b/spec/args/box_spec.rb
@@ -0,0 +1,108 @@
+require 'spec_helper'
+require 'squib/args/box'
+
+describe Squib::Args::Box do
+  subject(:box) { Squib::Args::Box.new }
+  let(:expected_defaults) { {x: [0], y: [0], width: [:native], height: [:native] } }
+
+  it 'intitially has no params set' do
+    expect(box).not_to respond_to(:x, :y, :width, :height)
+  end
+
+  it 'extracts the defaults from Box on an empty hash' do
+    box.load!({})
+    expect(box).to have_attributes(expected_defaults)
+  end
+
+  it 'extracts what is specified and fills in defaults from Box' do
+    box.load!(x: 4, width: 40)
+    expect(box).to have_attributes(x: [4], width: [40], y: [0], height: [:native])
+  end
+
+  it 'extracts the defaults from Box on an empty hash' do
+    box.load!({foo: :bar})
+    expect(box).to have_attributes(expected_defaults)
+    expect(box).not_to respond_to(:foo)
+  end
+
+  context 'single expansion' do
+    let(:args)    { {x: [1, 2], y: 3} }
+    before(:each) { box.load!(args, expand_by: 2) }
+    it 'expands box' do
+      expect(box).to have_attributes({
+          x: [1, 2],
+          y: [3, 3],
+          height: [:native, :native],
+          width: [:native, :native]
+      })
+    end
+
+    it 'gives access to each card too' do
+      expect(box[0]).to have_attributes({
+        x: 1,
+        y: 3,
+        height: :native,
+        width: :native
+        })
+    end
+  end
+
+  context 'layouts' do
+    let(:layout) do
+      { 'attack' => { x: 50 },
+        'defend' => { x: 60 } }
+    end
+
+    it 'are used when not specified' do
+      args = { layout: ['attack', 'defend'] }
+      box.load!(args, expand_by: 2, layout: layout)
+      expect(box).to have_attributes(
+         x: [50, 60],  # set by layout
+         y: [0, 0],    # Box default
+        )
+    end
+
+    it 'handle single expansion' do
+      args = { layout: 'attack' }
+      box.load!(args, expand_by: 2, layout: layout)
+      expect(box).to have_attributes(
+         x: [50, 50],  # set by layout
+         y: [0, 0],    # Box default
+        )
+    end
+  end
+
+  context 'unit conversion' do
+
+    it 'converts units on all args' do
+      args = {x: ['1in', '2in'], y: 300, width: '1in', height: '1in'}
+      box.load!(args, expand_by: 2)
+      expect(box).to have_attributes(
+        x: [300, 600],
+        y: [300, 300],
+        width: [300, 300],
+        height: [300, 300],
+      )
+    end
+
+  end
+
+  context 'validation' do
+    it 'replaces with deck width and height' do
+      args = {width: :native, height: :native}
+      deck = OpenStruct.new(width: 123, height: 456)
+      box = Squib::Args::Box.new(deck)
+      box.load!(args, expand_by: 1)
+      expect(box).to have_attributes(width: [123], height: [456])
+    end
+
+    it 'has radius override x_radius and y_radius' do
+      args = {x_radius: 1, y_radius: 2, radius: 3}
+      box.load!(args, expand_by: 2)
+      expect(box).to have_attributes(x_radius: [3, 3], y_radius: [3, 3])
+    end
+
+  end
+
+
+end
\ No newline at end of file
diff --git a/spec/graphics/graphics_shapes_spec.rb b/spec/graphics/graphics_shapes_spec.rb
index c0fa4c5..5f8a742 100644
--- a/spec/graphics/graphics_shapes_spec.rb
+++ b/spec/graphics/graphics_shapes_spec.rb
@@ -32,9 +32,10 @@ describe Squib::Card do
       expect(cxt).to receive(:restore).once
 
       card = Squib::Card.new(deck, 100, 150)
-      # rect(x, y, width, height, x_radius, y_radius,
-      #      fill_color, stroke_color, stroke_width)
-      card.rect(37, 38, 50, 100, 10, 15, '#fff', '#f00', 2.0)
+      # rect(Args::Box, x_radius, y_radius, Args::Draw)
+      box  = OpenStruct.new(x: 37, y: 38, width: 50, height: 100, x_radius: 10, y_radius: 15)
+      draw = OpenStruct.new(fill_color: '#fff', stroke_color: '#f00', stroke_width: 2.0)
+      card.rect(box, draw)
     end
   end