I made my own last year. I don’t like short strops, stropping a 270 or 300 knife on a 8 inch can be done just fine but after you use something a little longer it’s hard to go back.
I bought some roo leather, found some cherry wood I liked and made four strops, three went out to friends. They are 18” long by 3.5” wide. I loaded them with a Diamond spray on one side , .025 micron and a CBN emulsion on the other, 1 micron. I tried a lot of different products for strops on earlier versions of strops and ended up liking those. Many products worked great on before and after tests though. You can use whatever you want or nothing at all.
It’s an easy project. You can make the strop any size you want. You can use any leather you want. You just need the wood base, contact cement and the leather. I used roo leather, super thin, super tough, super effective. I also used a board that was 2.5 inches thick to get my finger clearance up a bit.