That is going to be a very cool ramps board, nice.
The printed pulleys are going to cause a small issue, so small I’m not sure if it will be measurable but you belt will not be inline because of them. This means your axis will move the tangent distance not the correct distance.Which will also change as the angle changes when it moves down the length. If you can move the belt attachment points at the end on the blocks you can fix this issue. A very small deviation but still a deviation. If it shows in your parts it’s an easy fix.