I have a folding trailer with stake pockets for the walls, made these for the retaining pins on the pockets so I don't have to reach around the other side of the trailer frame to bolt something in.
You will also need a 5/16" x 3 1/2" bolt (head should be 1/2"), 2 x 12mm x 3 mm round rare earth magnets and some jb weld.
The magnets are tight so you might have to press them in but the bolt should just drop in. The bolt is the retaining pin and this with the magnets keep the bolt in place.
spool 3d PLA