Derma mask?

Is there a way to have like a mask. What I mean is when using the paint function if I drew a rounded box, Can I draw anouther one ontop but instead of drawing ontop it likes cuts its out. So if I drew a big square, and on top a smaller one coudl i make that smaller one transparent and cut trough it?

It’s called stenciling, and yeah, it’s possible. I have some links but I’m too lazy to post them here, about to go to bed.

http://forum.facepunch.com/showthread.php?t=1449800

Cheers