Sure thing, mirrored acrylic cuts just like any other acrylic. There are a lot of posts about it if you want to dig through.
https://community.glowforge.com/search?q=Mirrored%20acrylic%20in%3Afirst%20%20%23beyond-the-manual
The trickiest part with mirrored acrylic is getting the power just right and avoiding flashback. Luckily there’s a really easy test method to get it dialed in, check out #4:
As for cost… it may be less expensive to buy a sheet of gold mirrored acrylic. Might be worth looking around. 20 3” circles is just about a full gf sized sheet, and you’d have much more control over how to cut a full sheet instead of just rounds.