another way I found to trim off the pesky curves, best is it is only $0.29
take 4 pennies,hot glue them together flush.
center a quarter on it and glue it also.
use a razor knife blade, and let the tip hang alittle lower, or just the same depth as the quarter, and glue it.
This will let you run the quarter along the edges, catching the curves,and score with the blade. it only takes off a quarter inch at a time, and you can keep the same curves as the original with out having to draw.
just score it and snap, or retrace a couple of times and cut.
Boozel