here's mine.
I moved 2 caps down, because over there the plastic is thicker. you can use sandpaper or a razor to scratch a bit of the casing, be careful not to overdo it, just enough.
Also, don't forget to carve a slot for the usb port. After that, you should be able to squeeze the pcb in your new cart.
It might still be a bit crammed, because the battery is quite close to the side of the cart, which makes it harder to slide it shut.
you could use a grey cart first to experiment on, before trying it on a coloured cart, because you can find them everywere
and remember to back up your sav file, just in case.. you never know.
all at your own risk of course.