I’ve mentioned my tape sandwich method before:
Mask your material.
Apply blue painters tape to the entire surface before you remove the material.
Remove taped-up piece, all the cut parts should come with it.
Flip and tape the other side. Now you have a tape sandwich.
Press the tape down thoroughly like you’re applying masking.
Peel the blue tape and masking off in a sheet.
You’ll miss a couple pieces, but that’s ok. It’s like 98-99% effective, which is good enough for me.
Now you have a pile of 423 unmasked pieces, quick and easy.
And in case you’re wondering, that’s enough parts to make 9 of these guys: