On a related note:
The Free Universal Construction Kit offers adapters between Lego, Duplo, Fischertechnik,Gears! Gears! Gears!, K’Nex, Krinkles (Bristle Blocks), Lincoln Logs, Tinkertoys, Zome, and Zoob. Our adapters can be downloaded from Thingiverse.com and other sharing sites as a set of 3D models in .STL format, suitable for reproduction by personal manufacturing devices like the Makerbot (an inexpensive, open-source 3D printer).