A while back I made a prototype of the sliding element for T-slot. Since then there were a few tweaks to it, however it was never really tried in action.
I received an email recently asking whether it was possible to use Contraptor to build contraptions of larger size (e.g. 2x4 ft). This would definitely call for T-slot - which I happen to have several standard lengths of (12", 18", 24"). I also have several fabricated T-slider prototypes. To test a number of assumptions about how these sliders would behave, I intend to build a robot with light X and heavier Y driven by belts, and heavy Z driven by four leadscrews. The robot would be ~2ft in X, ~1.5ft in Y and ~1ft in Z - but it could be scaled up. The actual work volume would be smaller than these dimensions. The screenshot on the right is work-in-progress on that robot.
So far I've assembled the basic T-slider belt drive. The test below uses Arduino GCode Interpreter and grblShield (1/8 microstepping). The speed is 600 IPM.