Go-Karts
Homemade go-karts can be made using ready-made kits, but they may also be assembled with items easily bought from hardware stores and even some things you may have in the garage. An old but functional lawnmower engine can serve as a go-kart's engine after it has been bolted and braced onto a frame. Frames can be created using either plywood or metal pieces and pipe. Steering, brake and throttle pedals, as well as the sprocket system, can be installed from kits or from scrap for more advanced hobbyists.
Remote-Controlled Cars
Remote-controlled cars go from mini-electric versions powered by batteries, to larger-sized versions powered by gas. Homemade remote-controlled toy cars give enthusiasts the chance to tailor a car to their own specifications. Gas-powered RC cars don't hold a lot of gas, but have the advantage of easy refueling, operate at fast speeds (often up to 50 or 60 mph) and have a longer driving time than electric counterparts. RC cars -- much like go-karts -- can be found in kit form or can be constructed based on the hobbyist's specifications.
Remote-Controlled Helicopters
Flying a toy offers new challenges compared to those that operate on four wheels. Gas driven remote-controlled helicopters are larger than other helicopter toys, making them more stable and more maneuverable in windy weather. Homemade gas-powered helicopter engines are similar to engines in leaf blowers or chain saws. Like RC cars, these toys are generally assembled from kits, but more experienced enthusiasts may put together circuit boards, bearings, and gears as well as the transmitters responsible for control.
Remote-Controlled Boats
Remote-controlled boats powered by gas often reach up to four feet in length. These boats generally use the same types of engines, but the engine must be within a sealed compartment to avoid water submersion, which will cause malfunctions. Remote-controlled boats are generally the least responsive in terms of steering and don't have the same risk as a helicopter or plane of hitting the ground and becoming destroyed.