Today we constructed our new design! We discovered while construction that we put the rollers a bit too low to have the same friction we had with our first treadmill prototype, so with our next model we will have to raise the hole for the dowel. Another problem we came upon is that there was a limited number of dowels that are the size of our holes so I think in the future we will have to make them bigger unless we find more of the dowel we were using.