Did you make those boards? Very nice!
I did the math, and 2oz in a gallon is a 1.5625% ratio.
The SO-Strong is used at a 0.01 to 3% ratio, so about the same.
When I was making the ThermoDipSticks, I mixed the resin by weight, enough to cast 5 at a time, I.E. a very small amount. The colorant was added by counting the drops from the bottle -- it has an eye-dropper type aperture on it. I think I was using 8 drops.
Yes, built( or restored) them.
I don’t use an exact science.
If you were using a mold like you were you could get away with far less. Maybe a half oz.
Again, I don’t get that scientific with it.
When it looks right, I go with it. Also, depending on how you are applying it, you will need more or less per the application.
Find what works and stick with it. Just throwing out another option with a lot of colors (there are far more than what’s listed on the site).