Background: Developmentally delayed children (autism, etc) need toys they can ritualistically take apart and reassemble. It is found best for the child if the toy-puzzle can be constrained to be assembled in only one sequence.

Specs:

Design and fabricate a toy that can assembled by a developmentally challenged child. Arrange that the assembly can occur in only one sequence. Test the toy on some children. Make the toy safe for use by children.

Use a CAD drawing system to define the parts of the assemble. Have the CAD file be used in the Rapid Prototyping machine to create the pieces out of ABS plastic.