We had one made from two rear ends from a couple of tricycles, steering was a bolted hinge in the middle under your knees.
Each wheel was made from two 8" squares of 1" plank glued together with the grain at 90 deg, and cut into a circle. A hole drilled centrally fitted the axle, and a bebt nail and washer kept them in place.
Nowhere to fit a brake of course.
Somehow we survived some steep streets and a long stormwater drain that could only be exited at half tide.
Full tide would be a drowning, low tide would be a broken neck on the rocks.
Cheers