A friend has the Brooklyn Revolver, and uses it constantly. She does a lot of Square in a Square patterns. As I wanted one, but didn't want to spend that much $, I tried an Olfa - they are square on a black square base. Didn't work at all for me, so I gave it away. Somebody said maybe I had a defetive one (it was hard to turn), so I tried again - same thing. Then I went the home made route; didn't like that, either. By then, I could have bought the darned Brooklyn Revolver, lol.
Finally ended up buying Martelli's when it was half off. Still ridiculously expensive, but at least it works - when I want to use it, which isn't as often as I thought I would.