I had two goals for this project, make some large-size nontoxic go stones (2 inches), and make some demonstration stones (1.5 inches with magnet). The biggest thing to note: I am not a crafter or DIY person at all. If I can do this, it probably means you can, too.
After a lot of research, I found 1.5-inch wooden domed discs for 13.2¢ in quantities of 100. Two-inch discs are 23.6¢ each in quantity 100. As an experiment, I went with the bigger 3/4-inch magnet.
Certified ACMI-AP. The Richart is much less expensive--the bigger bottle was $2 while the small bottle of Apple Barrel Acrylic Paint was $1. As you can see, the Apple Barrel covered much better in one coat than the Richart in two coats.
Once the edges are complete for about 40 of them and set down all in a row on newspaper, then I painted the tops. One coat of black seems to be enough! On to the white. One the white I was able to use a consistent technique learned from the black batch. The first coat went much quicker.
You can see both the 2-inch large stones and the 1.5-inch demonstration stones here. There were lots of lines and streaks on the white stones, so they needed another coat. I applied the paint in three major batches to give the paint in one batch a little time to dry before applying the second coat. Dry time between coats was maybe 15 minutes (but working continuously on the next batch). There was just enough paint in the small bottle to paint 100 2-inch and 50 1.5-inch stones with two coats. As you'll see the picture below, the backs are unpainted. Overall 1-2 hours to dry semi-completely, there were still small beads of paint that were wet.
Once dry, I needed to add magnets to the demonstration stones. After again researching supplies and seeing many references to E-6000 adhesive, I decided to try it. It apparently bonds to many different materials and the bonds is somewhat shock-absorbing (unlike Super Glue aka cyanoacrylate). Here's a somewhat "marketing oriented" video of its properties. The video was nice because it allowed me to see the viscosity of the adhesive before trying to use it (was it going to run? or glop on top? Answer: it glops and generally stays put).
They ended up great! And if you don't have the requirement of non-toxic, I'm sure it will be simpler with spray paint. I'm going to teach my 4-year-old nephew go using the 2-inch stones. I used non-toxic paint because there's a baby in the house and the less dangerous these are to all inhabitants, the more likely they'll be out for playing.
A few more refinements: My brief time with them appears the white/black may mark each other when rubbed together. I may want to figure out how to safely finish these with varnish, polyurethane, or spray shellac. I'll investigate and report later.
Now, who makes a board suitable for 2-inch go stones? Answer: I do, in part 2. Stay tuned.