A simple version of the rolling mouse trap. You need 2 standard skate bearing and a piece of 3/4 inch PVC. Please note that these were designed as a tight fit. I tapped in my bearing with a hammer and inserted the lid clip into the bearing with a monkey wrench. If you don't want a tight fit with the monkey wrench (it is hard to get in) you could 1-2% decrease the size of the lid clip.