This is fashioned after the bamboo bike trailer, with the addition of a seatpost mount and PVC instead of bamboo. I used the instruction for the wheel mounts, something I need to modify in the future to accomodate heavier loads to relieve axel flex. The PVC is 1" and the trailer bed is 12" wire shelving left over from a home remodel. The wheels are 20" front wheels with bolt-on axel. These are about $24 a piece unless you run a bike shop..hint,hint. The seatpost mount is made by TRAIL-GATOR.com and sells for around $15. My total investment was around $60 for this brand new trailer.
I left the bed flat to acccomodate various uses. We have mounted our dog crate, two plastic crates for groceries, and an athletic bag so far. Maximum load weight tested so far around 50 lbs. The trailer itself is very lightweight.