Simple little design that has a right and left hand 9/16-20 thread that allows you to keep bike pedals together when you're storing them. Just like most pedals, the left side has ribs so you can easily tell which side is which, but there are also “L” and “R” markings. (The ribs aren't seen on the ones in the photos as those were all early prototypes.)
There's a portion without threads so you don't have to thread them in quite so much. Fit should be good enough that you can thread in the pedals by hand, but I've found that different pedals fit differently.
Printing is easy as it doesn't need any particular strength, so draft mode is fine. The thread is 45 degrees, not the usual 60 degree, so you don't even have to worry so much about layer heights.
Note: pay no attention to the multi-color prints in the photos, I was killing off small remnants of filament while I was developing these. No functional reason for the colors.
The author marked this model as their own original creation.