weights of the chems to mix 1 liter final volume. That’s actually the smallest volume you can make using a mg scale.
.05 g silver nitrate, mixed in 50 ml distilled water- part A. .39 g sodium thiosulfate pentahydrate mixed in 50 ml distilled water- part B (Note- If you use anhydrous thiosulfate, you will need to do your own math.)
Whisk A and B together quickly for about 30 seconds. Add 900 ml of distilled water to reach the final 1L volume - I use 600ml here.