A simple cuboid box wih parameters for length, width and height. Changing these values and regenerating the model creates a custom size box.
The drawing file lets you export a DXF for cutting.
PTC Creo 2.0 Academic files and instructions are in the zip file.
How are teachers getting up to speed with the requirements for more CAD? Are there courses and is the government finding these?
D&T in England is going through a really bad patch with reduced curriculum time, finding cuts and almost no budget for CPD. Experienced teachers are being forced out to make way for cheaper newly qualified teachers. I am seeing projects being taught I did in school over forty years ago. Very sad. 
