...if you can dream it ...I can probably build it.
I once had a custom order from a government department for a 30-foot Mini-Monster course that their marketing guy dreamed up. Gravel mosh pit, jumps and obstacles. Was really fun to drive. Fortunately, they had the budget to make it happen.
And then there was the $1200 custom-built Lego track for 1/64th scale ...
...too bad Lego doesn't make 1/43 scale road tiles.