I would be interested in making one also, but I need to find a adjustable finger one so you can slide the fingers over together to be able to bend a small side up to the other two sides without the brake being in the way of the other two sides. Hard to find plans for that I guess.
I understand, I plan on adding a clamping device and a rail to add fingers to accept and allow for tab interference.
The mind has the ideas, then we go to engineering then to the production floor in my garage.
This should be a fun project.