As a kid do you remember wanting to use all your different construction sets to build one large project? I certainly do, and often times tried. I actually remember taping pieces from my K'Nex set to that of my legos. Well, thanks to 3D printing it is now possible to do this without the help of tape. The Free Universal Construction Kit, is available on Thingiverse and is a set of 80 different adapter pieces to connect any of 10 diffeent construction set pieces together. Whether it's Lego, Tinkertoy, K'Nex or others, they can now all work with each other. More details can be found here: http://3dprint.com/9147/3d-print-adapter-lego-knex/

Have you downloaded these designs and printed them? How did they work? Below is a picture of some of the adapter pieces: