Students from Computer Aps class finished MS Word, Excel, Powerpoint and a banking unit 1st semester so we found a 3-D drafting program online. It is AutoCAD/Autodesk's free version. So my high school students worked through the engineering process and then chose a 3rd grader for their "client". They designed the box together, then my computer aps kids drafted the project to scale on the CAD program with the boxes and pieces their clients chose. Then the 3rd graders came back and they assembled the project together. We started the unit by drafting smaller objects like buttons, chess pieces, a bed, and a log cabin.