4 wheel driving truck

I designed a small 4 wheel driving truck. The plans are available as both TurboCAD and .gif files. It is built from 9mm plywood cut with a jig saw, and fitted with Maxitrak wheels. I decided not to use springs, and the bearing supports are bolted directly onto the 21mm by 21mm timber chassis. This gives a firm ride, but I have had no derailments and a thick foam cushion seems to smooth this out well.
The main requirements were to have space to put coal and water, and a removable seat so that it could also be used to safely carry a small child inside. The foot rest is a length of 15mm copper water pipe.
The wheels and foot rest are painted with Hammerite xylene based black paint. This can be painted directly onto the base steel and copper, and only needs a single coat. It has proved very resilient with little wear on the foot rest. The wooden body is painted in water based wood gloss on a suitable undercoat. This is protected with yacht varnish.
I added corner braces made of 20mm angle iron painted matt black to strengthen the truck.