PCB mounted enclosed plastic rotary switch - general eBay -.
Dimensions based on - http://spec_sheets.e-switch.com/specs/G510440.pdf
Others based on - http://www.ckswitches.com/media/1349/arotary.pdf
More info - http://www.lorlin.co.uk/PDF/CK.pdf
There is slight differences in pin position between brands, ie 22mm to 22.2mm and 8mm to 7.7mm PCD, but the pin is 1mm in a 1.4mm hole so all should fit.
Rotary Switch 1x12
v1.0 - Rotary Switch 1x12.fzpz (20.6 KB)
Rotary Switch 2x6
v1.0 - Rotary Switch 2x6.fzpz (18.3 KB)
Rotary Switch 3x4 - 3, 90º centre pins.
v1.0 - Rotary Switch 3x4.fzpz (18.7 KB)
Rotary Switch 3x4 - 3, 120º centre pins
v1.0 - Rotary Switch2 3x4.fzpz (19.1 KB)
Rotary Switch 4x3
v1.0 - Rotary Switch 4x3.fzpz (19.2 KB)