At this stage I have moved from MDF to terra incognita -- cardboard. Its actually easier than it should be. The card bends easily along the creases and can be glued with PVA glue, for a quicker 'grip', super glue. Here is the cardboard 'growing' on top of the the MDF base
The wheels, believe it or not, are just stacks of cardboard. I would never have thought of that. Perhaps from the same spring of South African ingenuity that conceived of the Buffel in the first place.