The photograph shows the Rancilio doser model for which this replacement is intended. The STL's will provide a new doser bowl and plunger and lid. Once printed the bowl is easily attached with the existing Rancilio hardware fittings; firm as a rock (!).

You can find a video of it at work at youtu.be/0S_ugKZQhtQ. For those interested in the timer underneath the grinder, the PDF file includes the circuit schematic and sourcing details.

UPDATE 2013.04

There are now STL's for dual color printing so you can have a different colored "tell" on the chute. If you have printed the main part in black, it can be very difficult to see whether you already have a dose ground in the hopper. There is now an inset that you can print in another color - I use white - which makes it less likely you will "double grind" by mistake. The wide base flange you just cut off with scissors; stops all warping!