Sorry ren, it isn't a clue -- simply an observation. The clue was in Mags answer - fabric. I should have explained the word "it" as misplaced at the word was.
It is indeed, Tredici, a rotary cutter. Had bhs come in this thread, as a quilter, she would have identified it in a heartbeat, as did you. No felt, just a background.
I also quilt, and this is what I use to cut the fabric. The circular blade is sharp as a razor, so it is very important to get into the habit of closing it each time it is set down. I have a few scars to show -- I learned quickly to close it after every use.