I made two trumpets this past weekend and used a piece of 5/16" clear dowel to make the mouthpieces out of. One of the mouthpieces turned out OK, but you could still see the scuff(?) marks on the inside of the acrylic. The other one looks terrible on the inside where it was drilled out . I took my time and drilled out about 1/8" at a time. Go in a little, pull the bit back out the whole way to clear the shavings, repeat, repeat, repeat...you get the idea. It seemed to take me forever to get these pieces of acrylic drilled out. Don't get me wrong, they sound great, they just look bad as they are polished real nice on the outside and then it looks as if I drilled them out using sandpaper. any input on how to remedy this in the future would be greatly appreciated.