You can easily make your own interlock puzzle by a lasercutter machine, first cut drawing1.pdf with 6mm HDF plate, then turn pieces 90 degs and cut file drawing2.pdf as shown in images in attached zip file. Do not move the 6 mm plate between cuts. You can use it as a cup holder or a stand as well. I did cutting in Copenhagen Fablab.
After making the pieces the problem is that you should figure out how to lock them together :)). It is not symetrical, so be aware when you assemble pieces.