We bought a child's cart that hooks to the back of a bicycle. My dad basically gutted it to the frame, even taking off the tired (though they were rotted on this one), then removed the part that attached to the bike, and welded two bars on both sides. Since the wheels were rotted, we took the tires off of an old push cart (not convertible to a goat cart) and put them on instead, after painting the frame how we liked. The bars we welded on were very light and very bendable (with some force) so we could bend them in if need be, which has been needed as my doe has a very thin chest. The seat he made broke apart, so I won't explain it, but the seat we have now is a regular stadium seat that folds in, and we are going to somehow put it on instead. For clipping them onto the harness, he bought some gold (they also came in silver and black, its only color) clips from lowes for maybe $4 each and attached them through holes he put in the end of the pipes. To finish it off, he put padding around the ends of the pipes as well as down the whole pipe where it touches the goat, and we were done. It works great. My doe is still timid on it, but she has pulled it perfect before.