Malco hand seamer for the win! I use this to precisely fold my pucks up for a second squish. That's a 2x4 bag in the jaws that was folded long ways and then that folded in half. Makes a small dense puck and you can work the puck a bit to get the folds even. Big difference on yield on that 2nd go.
Hand seamer looks sweet! I do similar with an Irwin clamp. It does make a difference! I tend to use these clamps on pucks over 10g also. Just insert prepress cylinder I think I used the 40mm prepress for up to 14g.