The Free Universal Construction Kit

The Free Universal Construction Kit … is a collection of nearly 80 adapter bricks that enable complete interoperability between ten popular children’s construction toys. By allowing any piece to mate with any other, the Kit encourages totally new forms of intercourse between otherwise closed systems — enabling radically hybrid Constructivist play and the creation of heretofore impossible designs.

To be clear: the plans are free, not the parts:

[T]he kit — put together by F.A.T. Lab and Sy-Lab — isn’t a physical product unto itself; it’s a set of 3D models suitable for use with Makerbot and other 3D printer systems..

The Plans, from “uck”