Quick project.
I made this tool to get perfect squared off ends of wood. It was my second attempt as the first one was out by 1/2 a degree due to clamping drift
I found that even the chop saw can be off by fraction of a degree in at least one dimension and this tool leaves a very clean finish when used with a Ryoba pull saw.
The top block is a free sample of PlyBoo timber - Strands of bamboo compressed in a soy derived resin. It’s a dense sturdy material and and importantly the sample was perfectly square.
I used a Forsener bit to create cavities for the magnets* and drilled them a little deep, and fine tuned the magnet’s depth with bits of plastic then appleid epoxy when I was happy.
Getting ready to cut:
Square test…passed!
Magnets* of unknown strength bought in a 100¥ store in Tokyo.
The other options to square up by hand is to use a shooting board which is also great but not always convenient.