From the MAKE Flickr pool
J.Maz has refined the mousetrap car design and upgraded to a higher gauge rodent altogether –
the motor has been upgraded to a full-sized rat trap, which I drilled pilot holes in directly instead of mounting it to the 6″ 1×4. I also added a length of rod to the trap arm to increase the length of the arc and consequently the length of pull. This time I mounted the motor towards the front of the car, which reduces the torque while increasing the pull distance.
Check his Flickr page for more details. Good to see revisions/updates made to some of the more classic projects. Thanks for sharing! –Link
In the Maker store:
Mousetrap Powered Cars & Boats –Link