It's been a while since we've seen a good Altoids tin project, but over on Hackmypi, they have got a guide from stuffing the $US5 ($6) Raspberry Pi Zero and a touch screen into a tin.
The project here uses an Adafruit two-inch screen, adds in Bluetooth, Wi-Fi, and a full-sized USB port. All that's stuffed into the Altoids tin, soldered and covered in Sugru, then hooked into a 2000mAh battery. You'll obviously still need to use some type of external mouse and keyboard here, but the idea is solid. You'll find the full guide over at Hackmypi.