Mine are the big ones.. the original cart wheels and frame died, so I got one of those heavy duty garden carts and used the running gear from it.
I've also made the upright removable and put a seat cover on the back end. Also beveled the front edge, where that big box hits the cart and wrapped the handle in leather. In the future, I plan to wrap the edges in leather and secure them with brass tacks.
Adios,