Alright people dont laugh!! but depending on where you live and if you have horses, we have 10 acres, before i buily my track I just made a few jumps in the form of a track using horse manure lol, surprisingly it worked great, once that stuff packed down and dried it was great, and the truck never did stink, and the manure never got inside or outside the truck becuase once it is packed down and dried out by the sun it's like packed down clay!