excuse my ignorance:
I know what a sheet-metal brake is and how it - usually - works. In the pictures posted I see a continous piano hinge...
HOW does THIS brake work??
Here is a Quick sketch of the brake . It works quite well, and is worth the Effort to build . I have a 4 foot tinsmith box and pan brake that is none adjustable I bought new 15 years age, it is worthless for bending aluminum there’s no adjustment for setback.