can someone give me the lowdown on repro carts?

[ToastBucket]

Hey dudes. So I am a huge fan of the Earthbound series (but like, who isn't). I've kinda gotten tired of playing it on an emulator and not really being able to do any of the music related things. I feel like I'm losing a huge portion of the game. so basically, my plan is to just make an SP in a DMG and a repro cart to play mother 3. I know this is pretty unnecessary but I'm bored and want to make something because it's been a while.

Now to my real question. What exactly goes into making a repro cart? Is there more to it than just flashing the rom using a chip flasher? I can't seem to find any info anywhere and I know there's some people on here (Drakon?) who've done some repro work before

 

[Prog]

I *think* that you need to flash the EEPROM and transplant it into a cart that has a somehow comparable ROM. I dunno if mappers are relevant for GBA games or anything. Drakon won't be much help, he disappeared from the community after his terrible handiwork and business practices came to light.

 

[C4RB0]

This may help:
http://reinerziegler.de/GBA/gba.htm

It's about home-made GBA flash carts and programmers.

 

[ToastBucket]

I just bought one premade because the tools I would have needed to make my own cost about twice as much as the cart. I'm sure I'll be needing these tools for other things in the future so maybe I'll get into this later.