3D print rotary knob, small PCB with eg. grey code attached inside the knob, springs pressing pogo pins onto grey code disc
Turning knobs on DSLR as reference: https://d3nevzfk7ii3be.cloudfront.net/igi/meNesvULPoQvRX3M.huge
Those have 12 positions it seems.
Also interesting:
http://www.alps.com/prod/info/E/HTML/Encoder/Incremental/EC10E/EC10E1260502.html
http://www.alps.com/prod/info/E/HTML/Sensor/Position/RDC50/RDC50_list.html