you only need make a fun track ;)
in youtube you have many indoor circuits....... with the same dimensions ......... one nice example with a smaller dimensions
http://www.youtube.com/watch?v=shVBflj7K-M
SWORKZ BE-1, LEOPARD, HOBBYWING, GENS ACE, SANWA VX, FUTABA 3PL, MBX5R/T, RB5SPSL, FG MONSTER, TC5R, 808E, HYPER8, TF5, ZX5, NANO-TECH, HYPERION, 620DMG, ECO6-10, TEAM-IHOBBIES