When I build a Gameboy for someone, I like to flash a bootleg GBA cart filled with Gameboy+Color games so they have something to play immediately. I designed this cart label and will be ordering a sheet of them from StickerYou.com soon. Went with pastel colors.
Built my Boxy Pixel SP today. 900mAh Li-Po battery, V5 IPS screen kit, USB C charging port on the left side, aluminum shell and buttons. My gold triggers come soon. Had custom laser etching done in 3 spots.
I ordered a black aluminum cartridge shell from Boxy Pixel, and a couple of custom labels off Etsy to build my ultimate Zelda DX cartridge. It has an FRAM chip installed so it can save your game progress without the need for a save battery.
I'm designing a new slide-on shell solution for the official GBA Wireless device. If it turns out to be a good snug fit, I'll sell 'em. Mine are just 10mm thick. It also has a slot for the antenna portion of the PCB to stick out of.