The masking of the acrylic also makes a difference in edge quality. In the U.S., cast is almost always going to be paper mask. Extruded can be found as both paper and film mask. The film mask is much easier to cut, and it doesn’t require the top mask to be removed like cast. If the paper mask is not removed off the top, it is very difficult to get a smooth edge. The paper mask that is left on the top side is also very prone to flaming, which will ruin the piece if the burning is bad enough.