thats funny.. I was looking at metal shims that have the center missing but not thick enough. I dont know which would be better wood or metal over a long time period wood is easier all around. As are playing cards, with a hardwood frame instead of softer wood frame tables, wood is still the answer.
I'm old fashion big frggin flat head screw driver then add shim, remove screwdriver tap shim tighten screw. I 'm looking for long taper hard shims instead of soft ones, harder to find or overpriced to be productive. I guess I will stick to the screwdriver and shim/ playing cards.
I buy a 12 ft. X 3/4" thick board and cut my own purple heart shims on the band saw. The shims are 9" long and work fantastic. I get about 1000 shims for $120. and 4 hr. of work. I waste a lot of the wood when I break the shim off, but the table stays tight and the shims don't move.