Hard to find even decent pictures of mechanical press-brakes, tho’ there are a couple on the ‘net.
Aliexpress (and probably other F/E suppliers) still list a Mechanical Punch Press (see link below) which would make a good basis for a model, and I think there are probably enough pics & videos to suss out the basic mechanism & proportions, once you have those you can ‘fill in’ the detail and finish as you wish..
..unfortunately I can’t link to it, so you’ll have to search yourself, try cutting & pasting this term
“Aliexpress Mechanical Punch Machine / 100 Ton Power Press”
I know a Punch-Press isn’t exactly what you asked for, but the internet seems to be better furnished with pictures of these than mechanical press-brakes…
HTH