This is what I'm thinking:

• Get a ball bearing with an inner diameter >= the diameter of the lens.
• 3d print a gear with an inner diameter == outer diameter of the ball bearing
• Attach a linear polarization filter to the gear so it can rotate in front of the lens.
• Attach a stepper motor that drives the gear
• Use a TMC5160 silentstepstick, cut a trace and put it into motion controller mode
• Have the TMC diag pin toggle on "position reached" and have it control the shutter
• Update the position in the TMC to trigger on the next angle
• Add the images to a rotating buffer of size 4
• Use the 4 most recent images as textures to a GLES shader that calculates polarization angle.