Speedplay Cleat Wedge
Designed for Speedplay X-series peddles, but may fit others.
This is basically the plastic wedge portion of: http://www.bikefit.com/p-9-8-pack-speedplay-cleat-wedges.aspx used to change the angle of your Speedplay cleat to account for natural rotation of your ankle and possibly alleviate knee pain.
There are models for 2, 3 and 4 degrees of angle. Print with 100% infill.
You may need to find longer bolts for the thick side of the wedge. If I remember correctly they are M4s.