these are fairly easy to make, piece of ready rod, a dozen nuts to fit, dozen washers ground to the right diameter.
I recently bought a set of these ones sold by brownells, I have only used them a couple times, but I sure like them.
I have also made a sureform like tiriaq described and it’s okay, but I don’t see myself using it much now that I have the new ones.
https://www.brownells.com/gunsmith-...tting-tools/barrel-bedding-tool-prod6796.aspx