Parameterized Picture Mat

This script creates a rectangular “mat” of specified dimensions for use in framing pictures, with a cutout in the middle that the artwork sits behind. The default size is for a 3x4" frame.You can specify either a rectangular or oval opening, and the dimensions of the opening. If rectangular, you can enter a corner radius.If you use the OpenSCAD application on your own PC, you can create a “custom” shaped opening imported from an SVG file. Regrettably, SVG importing doesn't seem to work o