I wouldn't want to discourage anyone from making an investment to ensure future work, but just the raw material for testing is expensive.
I don't have D1.6 in front of me, but I think you will end up doing at least a 1/4 inch plate to 1/4 inch plate for the range of 1/8 to 1/2 inch. And you can do 1/16 to 1/16 to get you to 1/8 inch. You now have a range of 1/16 to 1/2 inch.
You might also consider qualifying to B2.1 instead of D1.6. B2.1 is more of an "all purpose" standard.
Al