Instead of trying to cut the finished length and the angle, I instead used a mini belt sander to carefully sand them down to the finished shape.
To assemble the elements into a final part I cut a piece of luan to work as a backer. I initially marked off the position of each element but found that this wasn't the best way to assemble it accurately.
Instead I cut a series of small blocks that matched the distance between the elements. I glues in the first one and then use the blocks to get the correct spacing for the remainder.
Here is the finished coin slot assembly.