Here's a few photographs of my first home-made wagon. I needed a brake-van of some sort and funds are tight. I purchased a couple of flat bed Hartland chassis from Back2Bay6 and a few hundred coffee stirrers off e-bay with a view to seeing what I could do. Having looked at photos of other home-made/kit built/real brake vans I designed mine 'on the fly'. The starting point was the six square holes in the flatbed that I used as anchoring points for the uprights of the body. The body remains removable. I won't bore anybody with construction details as I think it should be fairly obvious from the photos. I added thin plasticard strips embossed from the rear with a biro to give the impression of bolt heads. The tail lamp works using a 3V LED and 2 x AA battery pack slung under the chassis with a small slidey switch. I changed the plastic wheels for metal ones (and this with the batteries) adds plenty of added weight. The roof is muslin covered coffee stirrers painted mucky grey with rain strips added. The main paint used was Halfords red primer rattle can with black bits picked out in black gloss Humbrol or red gloss Humbrol for the buffer beams. The main thing for me was that it was fun and it's all mine. My thanks to The Fat Controller (Steve) for the slidey switch.
Like the van (and the working tail lamp). 
and I think a wider board would make it even easier to break.