I forgot to finish these, and left the masking fluid on one for several days (it should come off within 24 hours) It still removed easily and did no damage. It is that Molotow masking pen, 2mm… (link here)… and does really well on tiny spaces.
Remember, and ATC (artist trading card) is 2 1/2 ” x 3 1/2 “… a very small space for painting a lot of detail. How many watercolored ATCs do you think are equal to a set of hand knitted or crocheted fingerless gloves?? It’s a swap, and I feel like 4 is not nearly enough.