I'm going to build one here shortly, but I'm doing the box type. I have to many hills I travel and with just an "L" shape carry all, everything would fall off of it.
I've thought about these but I think I'll look for a set of 3pt pallet jacks. Then I can build boxes on pallets for firewood, etc. I could have two or three boxes filled with firewood and just move one up to the house as needed.
I have one of those. I am going to use it as a base for a logging winch. Winch will be here Monday. Hydraulic Mile Marker. Will post pictures once I get started.
This is my version of the carryall built around a set of rear forks. All sides are removable and the base just slides onto the forks so it can be removed quickly if I need to use just the forks.