The StorageBot frame is constructed out of pine wood. All of the materials can be purchased at Home Depot. The plastic storage bins can be purchased from Harbor Freight. See the attached bill of materials for quantity and pricing.
When buying pine wood from Home Depot make sure you spend time selecting the best pieces of straight wood. I found the wood at the top of the stack is typically the most crooked pieces. Some of this lumber may be returned items and obviously people would return the worst of the pieces. Here's a trick to help determine the straight pieces. Place the piece of wood on the flat concrete floor and use the floor as a straight edge. Stay away from wood that is twisted along the length. Long pieces of wood that bow slightly in the middle can be ok if a later process such as screwing into the final framing straightens them out.
I modeled the pine frame using the free 3D CAD program from Autodesk called 123D. You can download the program here:http://www.123dapp.com
The cool thing about this program is that you model the components of your systems and then connect them together using something called constraints. In 123D constraints are under the Design Intent \ Assemble Icon. With constraints I can tell 123D to take 2 separate pieces of pine wood and align the edges to each other. Another useful feature of 123D is the Browser history along the left side of the screen. With this browser I can easily turn components on and off by just clicking an "eye" icon for each component. I used this feature in order to generate the step by step images for the frame construction.
The 123D model of the pine frame is attached below as a zip file. Have fun playing with 123D and be sure to watch the tutorial videos on YouTube.