Gotta be a custom build; not rocket science but expensive. Cookers like this that are made to cook every day in a commercoal/retail setting really need to have stainless cooking grates/baskets and some kind of protection for the cold rolled charcoal box (i.e, firebrick lined), especially burning lump. That trailer rig has to be one heavy sucker! The chain drive/sprocket system is the easy part. Just my $0.02.