I use cling vinyl from the fabric departments of JoAnns or WalMart. It's important to purchase the correct weight. You should buy the medium-heavy weight.... it's the kind sold by the yard that you might cover a picnic tablecloth with, or outdoor furniture. If you buy the heaviest weight, it's too heavy and will fall off your block; same with the light-weight - it's too flimsy to cling.
Eventually, with glitter, glue, ink, powder, hair and dust, the cling vinyl gets dirtied up. Take a drop of GooGone (GGP#16) and rub it over the cling vinyl, and on the acrylic block. Wipe off excess by dragging across scrap paper, and polish with a lint-free cloth.
The GooGone cleans and rehydrates both surfaces so the cling will stick again.
Cheryl
OnyxXpressions