canvas

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend();

application.template.hbs

<h1>Square Drawing Software</h1>
{{window-component}}

canvas-component.component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

canvas-component.template.hbs

<svg xmlns="http://www.w3.org/2000/svg" width="600" height="600"> 
 <rect x="20" y="50" width="{{width}}" height="{{width}}" fill="{{color}}" />
</svg>

models.square.js

import DS from 'ember-data';

export default DS.Model.extend({
  width: 100,
  color: 'red'
});

toolbox-component.component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

toolbox-component.template.hbs

Width: {{input type="text" value=width}}<br>
Color: {{input type="text" value=color}}

twiddle.json

{
  "version": "0.4.11",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.11/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember-template-compiler.js"
  }
}

window-component.component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

window-component.template.hbs

{{toolbox-component}}
<hr>
{{canvas-component}}