My friends and I are having a little challenge. We want to come up with the cheapest open-top, but sided cargo trailer possible. It must use completely new parts freely available from local steel/wood/plastic suppliers and be capable of hauling around 800lbs. Labor must be something that your typical hobbyist woodworker or welder could do. My idea is something like this: have the sides and floor of the trailer made of one piece of heavy duty expanded steel, bent as appropriate. Attach an axle or two individual wheels on the sides. However, I'm having a lot of trouble finding the cost of such metal. I'm really looking for expanded steel where the steel strands are about 0.5" This should make it strong enough to hold its own structure and take quite a load. It would be awesome if I could find that rubberized stuff you're likely to find in a factory or construction site. Ideas?