Finally, someone else! I thought I was all alone here in the home of Das Keyboard.
Yeah, the key caps are currently polycarbonate with a custom layout and shape. They are really what distinguishes the board from something like ErgoDox. I mean, it's a great kit, nice case, nice firmware, all done by folks who know what they are doing. But to me the key caps are the real value add.
Any requests for interesting keyboards to bring? I have a 107 key Model F, a Displaywriter beam spring, and a Topre HiPro and 55g board. (I have lots of other boards too.)