On Thursday, March 16, 2017 at 9:25:05 PM UTC-7, pyotr filipivich wrote:

....heck with a foot long piece of 4.5
inch diameter stock, I could just use it as a weight to hold it in
place.

Yep; an alternate book press design would be two granite plates, 9"x12"x3".
One on the bottom, one on the top.