Everything that I can think of would look convincing is similarly messy- but instead of altering the thinset or grout, you could swap out a skin that’s getting tiled by installing luan (or something similar) over the area that’s getting tiled in small enough sections to be able to remove and replace sections of it during resets. Thinsets have different working times, so make sure you get one with a long working time so its less likely to solidify during filming.
maybe just mix mortar with mineral oil….?
Everything that I can think of would look convincing is similarly messy- but instead of altering the thinset or grout, you could swap out a skin that’s getting tiled by installing luan (or something similar) over the area that’s getting tiled in small enough sections to be able to remove and replace sections of it during resets. Thinsets have different working times, so make sure you get one with a long working time so its less likely to solidify during filming.
That’s a good thought, thank you!