Hey nice! That looks like one that could work, just make it bigger.

Maybe a 4"x4" by 2 feet long or so? Cut out an arc of wood from the top just like that one you have in the picture, and stretch leather across..

Next I'd try to think of an easy way to tighten it when it stretches/loosens.

Essentially one piece of wood, leather, and some hardware.

So vegi tanned is the way to go? I think I read that there's a difference in pull between bridle leather and others. Less pull was easier for me, but with experience maybe that preference would change.

I'd like to have a pasted paddle strop and a loom strop I think. Seems a lot of guys use that combo?

Thanks guys! Much appreciated