This is what I've used!
https://www.amazon.com/gp/aw/d/B08MQ79VS1/ref=ppx_yo_mob_b_track_package_o0_img?ie=UTF8&psc=1
Now, these are really large sheets and I got 20 of them, which is going to last me for literal years. I got too much. Don't make the same mistake I did unless you're gonna use them constantly.
I just ended up cutting them into small strips. When you're ready to use them, bunch them up into a little ball and use some tweezers to dunk them in resin to try and minimize the chance of bubbles getting trapped and running your dice. Then stuff them into your molds and pour everything else on top of them, it'll fill in the open spaces around it.
Good luck!
20pcs Cellophane Wrap Paper Clear Rainbow Color for Birthday Mother's Day Valentine's Day Christmas Gift Candy Package Flower Wrapping 20.5" x23.6" https://www.amazon.com/dp/B08MQ79VS1/ref=cm_sw_r_apan_i_99WZA8S7K1K545CTTER4?_encoding=UTF8&psc=1
This one has worked great for me.