'Tis a bargain, indeed! Only issue I see is that most framed artwork like this uses extruded acrylic instead of cast…and I’m betting that’s the case with this. Extruded doesn’t engrave very well, and though much smellier, cuts just fine.
Although I have a lot of extruded acrylic from Lowe’s and haven’t had a problem with it engraving. It may not be quite as sharp maybe, but it still works fine for keychains and everything else I’ve used it for. I never would have thought at looking at thrift shops or yard sales for pictures that might have acrylic in them.
I just use the standard GF settings for either medium or thick acrylic. I always either use either dish soap on both sides, or like in these keychains, wood glue (dried) on the engraving side and dish soap on the other.
What @ca_worth said. Also, it seems to give a smoother, more rounded edge, whereas masking makes a “ridge” on the edge. And it is so easy to wash the soap off, so there’s no weeding. I started using @evansd2 wood glue for when I want to engrave, as it is super great for preventing bleed-through of paints, whereas paint has more of a tendency to bleed through with masking. And the wood glue is easy to weed off too - I usually use a straight pin, which is great for getting tiny spaces in letters, etc. - you just have to be sure to go at an angle with the pin so you don’t scratch the acrylic.