DIY Keyboard keychain
This keychain was generated from Rhinoscript code that is stored in the repository. The key is defined parametrically, so parameters like the keychain height and width can be changed easily. Drew created this model to demonstrate Rhinoscript to the DIY Keyboard crowd. If we design the entire keyboard this way, it will be possible to specify things like the octave spacing of your keyboard with a single parameter!
An experimental key profile design is in the files section of this page. It was generated by postscript code that is in the subversion repository (currently hosted on google groups).
Resin Casting is an attractive option for low volume manufacturing of parts with complex shapes. You typically use your prototype to make a latex mold, then pour epoxy resin into this (re-usable) mold.
A resin casting materials supplier in Chicago
3350 W. 48th Pl.
With the proper tools and lots of time, one could make beautiful custom piano keys out of wood. However, the relative complexity of the shape of Janko keys would add significantly to the expense of such a keyboard. You'd either have to fashion each key out of multiple pieces of wood (This seems to be the way acoustic Jankos have been made), or you would have to do a lot of carving/routing.
Injection Molding is how commercial digital piano keys are made. This is the best option for very high volumes, but the high cost and low flexibility of mold-making puts this out of reach of most hobbyists.