Armed with an empty cereal box - or similar - and a few 3D printed parts, you can keep your child engaged for quite a while as you both construct a Cereal Box Townhouse!

The original design comes from Dadhoc on Thingiverse: http://www.thingiverse.com/thing:163746 and this set of parts consists of three windows (only two shown in the photograph below), one door, one door frame and all of the necessary brackets and stencils. Additional windows and doors can be printed as needed  so that you can go as large as you want.

Take a look at the gallery of photographs here to see what others have made from my kit of parts.