Estes Klingon Battle Cruiser, #1274, Build Part 3, Vacu-Form Parts Cutting

Make light cut passes until you can easily crack off the scrap sides.
If it doesn't crack easily, lightly score it with your knife again.
Work in small sections, don't try to cut the entire shape out at once. Cut past the ends of the pieces.





Here's how my Hull Top piece looked before sanding the edges.
I left myself plenty of overhang. This will be sanded down with 220 grit on a sanding block.

Here's a before and after of a wrap drive half.
On the left I didn't initially cut close to the wavy edge. It was rounded off and came to final shape during sanding.

Sand until the overhang edge is thin and bendable.
Fold the edge to the inside and it'll sand off easily.