How to nicely take apart Nintendo DS cartridges

My endgame is to make custom game cartridges from resin, which is already a project that’ll take some experimentation. Of course I plan on tackling cartridges from other game systems, but my sights are set firmly on DS first because I want Pokémon Diamond and Pearl to actually look like a diamond and pearl, dangit. The hypothetical process should be

-take a cheap sacrificial cartridge apart

-make a silicone mold of both sides

-pour resin in the custom molds

-add decorative glitters and paints and papers and whatnot

-cure the resin

-switch the inner chip and sticker label to the new resin shell

-put it together somehow????? (glue?)

-test the end result to make sure it still functions

-reuse the mold and repeat steps 3-8 for future projects

-happy sparkly gaming days

I just got the Essential Electronics Toolkit earlier today for my birthday, so I immediately used it to pry apart a cheap DS game I had laying around. I got it apart, but only through brute force. I ended up leaving scratches and scuffs and even cracked the plastic. Any bits of damage done to the shell will end up transferring to the mold and final resin piece, so I want to be able to minimize that. Since the first one ended up being such a disaster, it’s clear to me i’m going to have to try again with other cheap games until I can get it apart without breaking the whole thing.

So aside from sticking tools into a groove and prying and slicing at the plastic seal until the two halves separate, does anyone have any better ideas on how to take these things apart?