The case I designed for a smartwatch built using the excellent Microsoft .Net Micro Framework and an ST Cortex M4 micro controller chip and a sharp memory display.

All electronics and software design was done by the very talented @Justin from http://ingenuitymicro.com/

Links here for more information:-
http://iww.ghielectronics.com/community/forum/topic?id=17105
http://www.ghielectronics.com/community/forum/topic?id=16298
http://www.ghielectronics.com/community/codeshare/entry/954

This is a DesginSpark Mechanical CAD model of my case for the Radius.NET watch as created by @Justin.

DesginSpark Mechanical is available for free and can easily export the files as STL for printing or to Sketchup if you prefer that.

The watch is designed to use a 40mm x 1mm glass and a 18mm watch strap. Both are readily available on ebay. I have found that a UV Glue (as used for attaching smartphone screens to their digitisers works well to attach the glass again available from ebay.

I have printed the case using SLS in Nylon.Most fused filament printers will not have the required resolution to print the part well. EDIT - I just printed this at 0.1mm layer height with 0.4mm nozzle on my Wanhao i3 and it turned out really well using Simplify3D default support.

On mine the holes for the pushers needed drilling with a 4.5mm drill bit and the holes for the strap spring bar needed drilling to 0.8mm (1mm seemed to work for me though).

Note :- this initial version is a bit tight in the Z axis as I didn't leave any tolerance between the display board and the pusher. This means that the back of the case does not sit flush and the buttons do not move as smoothly as I would like.