31 July update
I lowered the rubber wheels so there's more ground clearance. I also lowered the middle shelf and the bottom shelf so the folding arms don't block the shelving as much. The bottom shelf is a bit buried now, so I only put stuff down there to get things out of the way.
29 july 22
This folds up! Also, I made this entirely from scap wood and leftoever hardware i had in the house. Nothing new was used to make it. click here for more photos
The larger wheels above are likely a temporary addition, I'll revert to the small casters below when done working on the truck probably. It's lighter to carry and folds up better with the caster wheels, but the caster wheels don't roll well over lawn or my paver sidewalk.
i especially like the use of these fence gate anchor pins. They're normally used vertically and they're meant to keep fence doors locked in place. But I made them work.