MintyPi V2

Parts List

Altoids tin (I don't think size varies between countries, but the ones I've been using are from the US). You can also use the blank tin that Adafruit sells, as it's an exact match in size and shape: https://www.adafruit.com/product/97
Raspberry Pi Zero W (the older non-W version will work fine, but wifi is very nice to have for transferring roms and SSHing into it to tweak settings, since the USB port is taken up by the sound card)
3D-printed parts to hold everything in place (I'll have those available soon. STL files will be available at some point in the future.)
Screen: either the 2.4" screen with custom PCB that Helder will have available soon, or a 2.2" ILI9340-based SPI TFT screen like this one:

http://www.ebay.com/itm/252135075697 (It should look identical to this one on the back. You may be able to find cheaper sellers. There is a thread for discussing screen options here: http://sudomod.com/forum/viewtopic.php?f=30&t=2887).

USB sound card (this one specifically because of its size and the fact that it puts out enough juice to not need a separate amp to drive a tiny speaker: http://www.ebay.com/itm/112304879364 -- again you may be able to find a cheaper seller)
Speaker: 20mm diameter 0.5W 8Ohm (this is the one I used, but any 20mm speaker that is 3.5mm or less in thickness should work: http://www.ebay.com/itm/122331730209 )
Charger: Either the Powerboost 500C from Adafruit (https://www.adafruit.com/product/1944) or a tiny battery charger like Adafruit's microLipo (https://www.adafruit.com/product/1904)
Battery: 1200mAh lipo from Adafruit: https://www.adafruit.com/product/258
DS Lite buttons and conductive pads (DSi, 3DS and n3DS will NOT work with the 3d-printed parts or the button PCB that we're working on. I will have white and black buttons available.)
Power switch: (I used this one since it's available locally for really cheap, but any tiny switch should do: https://www.adafruit.com/product/805)
Tactile switches: 2 for start and select - these 2 will be pre-attached to Helder's board - (2.5mm tall including the actual button, 2mm tall without, 6.2mm x 6.2mm base), and 2 for L/R (5mm tall including the actual button, 3.2mm tall without, 6.2 x 6.2mm base)
If you want to do it all by hand in stead of using a button PCB, then some copper tape like this: https://www.amazon.com/Copper-Conductive-Adhesive-4inch-36yards/dp/B01CH4LYZ6/

RetroPie (the Raspian-based bundle of emulators and frontend we know and love): https://retropie.org.uk/
fbtft (SPI screen driver): https://github.com/notro/fbtft/wiki/LCD-Modules
fbcp (copies the framebuffer to an SPI/GPIO screen): https://github.com/tasanakorn/rpi-fbcp
Retrogame (turns GPIO into keyboard input): https://github.com/adafruit/Adafruit-Retrogame

A pre-configured RetroPie image will be available soon.