All I'm making is a sanding board. It works better than a file or rasp and doesn't dull your good plane blade.

My mistake, I usually make it with 60 grit (course grit sanding belt) Just use it like a rasp.

It's nothing sophisticated. You just can't buy something like that. So I don't confuse you. 2 or 3 " wide x around 10 or 12 piece of 3/4 pine scrap. Glue on 60 grit sanding belt material with carpenters glue. You would press the belt material down flat with another piece of wood. So you just press it down with another sandwich of the same facing it so you get two at the same time.

I just use some spring clamps.