Height to axle is 25 inches. The frame is built of scrap 2x4 lumber and a plywood base held together with screws. It is sized so that it will just fit in the back of my Toyota station wagon or else bolted on top of it. The bearings are just a couple of holes drilled in the wood. Bore two nice holes with a forstner bit and saw down to form a round bottom notch.
Mold is made of two plywood arcs with holes at the center.
Nail two wood squares on the ends and sheet metal on the bottom curve. Cross bar deep inside keeps them from pulling out. A long bar through the pivot holes and mold sides keeps all in alignment while the concrete sets. Reinforcing rods inside keeps weight from flying apart in case of cracks. Keep it damp and let it cure 4 days.