I built a homemade trailer, mainly just for fun. Used it to haul some junk to the recycler, etc.
I took a piece of angle aluminum, drilled a hole on one angle for the axle, and another hole on the other angle. I rounded of the corner of this angle, and then put a quicklink through it. Quicklink goes through a hole in the trailer pull bar, done.
It's bulletproof, but it does have some play in it. It's never bothered me, and it cost me free dollars.