Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5981855.

This is an adapter so that you can use a normal doorknob as a one-sided dummy doorknob. The part called "bolt hole arm" inserts in the existing hole on the side of the door and locks into the insert to prevent it from turning when someone twists it. You can read more about this design on my blog.

This design supports the Kwikset knobs that I had on-hand. If you want to modify the design for a different doorknob shaft profile and length, fork my Onshape project.