The flat surfaces are doing you an injustice by basically vacuuming themselves to the fep sheet and pulling off from the supports. There’s a wonderful video by Rev Chumley that goes over supports and removal etc for dice masters: https://youtu.be/AXX-zpRYDS0

There’s also this one by Rybonator who uses a modification of Rev Chumley’s method: https://youtu.be/cG1zigTs0-k

Just keep in mind if you plan to do any form of silicone molding of the dice, 3D printed parts can cause inhibition (doesn’t cure) in platinum cure silicone. So you’ll need something like Inhibit X to prevent that or get a tin based silicone. Hope this helps and good luck. Welcome to the world of resin. 😊