How to build a motorized skateboard?

Hello, I want to build a motorized skateboard, gas or electric. I'm pretty handy, but am not that advanced with motors. I was wondering what I could use and how to assemble it to make one, a remote would be nice, but not mandatory. I'm open to suggestions, such as chainsaw motors, lawn mower motors, etc. But please explain how I would need to put this together! Thank you very much!(: (Also, I don't want to go buy a kit from a store to do this, I want to make it homemade!)