One idea: Buy one of these (https://www.harborfreight.com/150-lb-capacity-foldable-hand-...) and turn it into this (https://images.turnto.com/media/t7kuhATX6jW2ChSsite/5A481415...). If you want to keep it foldable, instead of an axle going all the way through, use either a long bolt or threaded rod, with nuts and lock washers, to attach a smaller pneumatic wheel to each side (threaded rod goes through plastic enclosure, nuts/lock washers keep it locked on either side of plastic housing, wheel fixed on outside with bushings or cotter pin)
