Its promising to hear some people have come up with their own homemade varieties as this precision equipment is normally prohibitively expensive for a model engineer.
Hi john, i do know someone who has a surface grinder, the type of one with a reciprocating table and maybe he'd do it for a reasonable price, it would be no doubt the best material to go for if you want a sturdy flat base.
and Michael, I haven't seen anything like that before, it looks pretty neat – ex industry? reminds me of an old fashioned Smiths RPM gauge set, complete with rubber tipped inserts, that was given to me on the off chance, maybe i'll put some pictures of it up. Its nice to see these old devices people have sometimes forgotten existed. I've already used mine to make an RPM chart for my inverter.