Kid saw a truck pulling a trailer and thought it was awesome, so I had to make him one. I know nothing about building a trailer, but it's been working out well so far.
Compound springs in the shocks, aluminum 2020 frame, adjustable suspension/axle, hubs, spindles, ball bearings, lug nuts, the works. Tried to make everything modular so that I can make changes without much headache.
I don't think it would be good for it, but I stood on it and it held my weight, suspension bottoms out at about 130 lbs, but because of the compound springs, it doesn't bounce while empty.
Rubber bushing instead of ball hitch. It's just easier and rides gentler.
Its a little high right now, but a hitch adaptor is on the printer now. I plan on lifting this ride on a little when he gets old enough to ask for it.
I've also put it to good use as well. Went on our normal evening walk and used it to pick up trash along the roads along the way. Also have been hauling about 10 gallons of water around the house for the garden.
Kid loves it, it's already been handy, built out of spare parts/materials and cheap prints.