Engineers who work at Dyson of vacuum cleaner fame are lucky. They get to do cool things during their off hours using company resources. For one example, check out this video of an in-house competition to determine who could build the fastest model car using old motors from Dyson vacuums. The motors incorporate rare-earth magnets so they are pretty powerful. One guy mounted an office chair on his entry to produce a go kart of sorts:
In another case, Dyson engineers routed a balloon through a course made up of the firm's Air Multiplier fans: