This is my first go at making a left handed thumb throttle for my atv. It was quite the learning experience. At this time I just got the privileged to use a Tormach pcnc 1100 mill. So first off was designing the whole thing in inventor. Then with my fathers help we made a aluminum casting of the throttle body. It resembled the throttle on the outside, but I left the inside alone so I could mill everything exact later. After the inside was milled I milled the top square off that I was using to clamp to. After a lot of sanding and grinding it started to take shape! The throttle cover was pretty easy seeing as it was only 2d, and I added my little cow logo to it to give it my little personal touch. The thumb lever was a bit tricky. What we did was carved a crude version of it in foam, and then cast it. The aluminum melted the foam and took its place. After it was cast I just had to cut the scrap off and then sand it to the shape I wanted it to. After that was done the throttle was pretty much done. I stole the inner linkage and the clamp that held it to the handle bar from the original right handed throttle.