I made these for a stand we held at Kids Expo in Norway (For Kodegenet), where we among other things showcased 3D printing and coding for kids. The blocks where fun for the kids to play with, and it was a simple project that could show off 3D printing on a level that anyone could get and understand.

The slots in the blocks are tilted slightly, so that they will snap-fit better multiple times, even when printed with PLA which is not as elastic as ABS.

This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/ff1kDnj44D7