The photo below shows the results of a styrene cutting test using a Silhouette Cameo die cutter. The TOS insignia was entered into the Silhouette Studio software as a font character from the Star Trek Font Pack
(remember that?). Since the character is a vector, I didn't have to do anything to it to get the cuts the way I wanted.
After a couple of test cuts using 65 lb card stock, I tested cutting .010, .015, and .020 styrene. I fooled around with the settings a bit and got pretty good results in all three thicknesses. The machine cut completely through the .010 and .015 styrene (though it did require the use of the "cut twice" option) and scored the .020 enough that I was able to "snap" the pieces out fairly easily. I would be hesitant to stick anything thicker than .020 into the machine. My guess would be that you'd get scribed lines that would be useful for guiding you in finishing the cut with a knife, but probably nothing more than that. (That, in itself, could be useful though.)
The largest piece shown below (the outline) is roughly 1.5" tall.
Due to the small size and delicate nature of the "star" in the center, snapping it out of the .020 styrene was a little bit challenging. A couple of swipes with a knife along the lower legs, however, and it came right out. I would imagine that snapping out something with mostly straight sides would be a cinch.
The edges of the cuts showed much less piling up of excess styrene around the cuts than I expected (maybe because the blade is brand new). On the .015 cut it is almost non-existent and on the .020 I think it would be trivial to remove.
While my goal was to actually cut out a shape, I can see how this machine would be very useful for someone wanting to add detail onto a piece of styrene without cutting all the way through it.
I chose this shape because the curves are complex, I could control the size, and it had a couple of different shapes embedded inside of each other. The curves that were cut are absolutely perfect--beautiful.
My total experience with this machine is less than an hour but I can say this: I could never have made those complex cuts by hand without distorting the original shapes.