Hi
How about using these?
https://www.ebay.co.uk/itm/231999683...0AAOSwZ1BXd4pL
Could use them as they are, or file/grind the hex section off, even cross hatch them.
Depending on your equipment, you could take the hex off by screwing a bit of studding into the nut and putting it in a drill. Then take hex off by rotating against a file, emery cloth, or grinder.
A lot less work than making from scratch.
Richard
PS no direct ebay discussions please as per forum rules.