The front wheel is a little less important — it can be large or small. For a classic drag racer look, you’ll want big wheels in the back and smaller ones in front.
Old CDs or DVDs work fairly well for this purpose — they’re large, thin, and extremely light. In this case, a plumbing washer may be used to reduce the hole size in the middle of the CD (to fit the axle better). If you have access to old vinyl, these also work extremely well, though they may be too heavy for the smallest mousetraps.
Narrow wooden dowel rods are a great, easily-accessible choice here. If you have access to thin metal rods, these are even better — when lubricated, they usually have less friction.
Electrical tape Rubber bands Popped balloon rubber Additionally, placing a piece of sandpaper under the rear wheels at the start line can reduce slippage as the car begins to move (when it is most likely).
Balsa wood Hard plastic sheets Thin, light metal sheets (aluminum/tin roofing material, etc. ) Building toys (K’NEX, Legos, etc. )
Remember, to minimize drag, you’re trying to give your car the narrowest, smallest profile possible. Try getting down on the ground and looking at your car from the front to spot pieces of the frame that make your car’s profile unnecessarily large.
Another advantage of glue is that it shouldn’t usually affect your car’s air resistance. On the other hand, if either end of a nail sticks out of your frame, it can have a minor effect.
If you’re using an extra-fragile material like balsa wood and you’re having a hard time getting your frame to hold together, consider adding a small strip of a sturdier material like metal or plastic on the underside of the frame. Doing this increases the structural strength of the car while minimizing the change to its air resistance and weight.
It’s important to use the right material for your lever. The lever shouldn’t bend at all under the stress of the string — this represents wasted energy. [3] X Research source Many guides recommend sturdy balsa constructions or balsa reinforced with metal to give a sturdy yet light lever.
Many mousetrap car building guides identify the axle as the primary source of friction on a mousetrap car. [4] X Research source To minimize axle friction, rub or spray a little lubricant on each axle where it meets the frame, then, if possible, work it into the contact point by sliding the wheels back and forth.
Keep in mind that rat traps and other large rodent traps can easily break fingers, so handle armed traps with extreme caution, even when you’re confident that the trap is rigged up to your axle and shouldn’t be able to close freely.
