While you can install Linux on just about anything, old tablets are probably the cheapest way to do it. Case in point, Node put together a guide that repurposes a Nexus 7 tablet and converts it into a micro-sized laptop.
The process here uses an old Nexus 8 tablet, a 7-inch keyboard case, a USB port, a USB plug, and some thin plastic or cardboard. You’ll start by getting Ubuntu installed on the Nexus, then just combine everything else together into a case to resemble a laptop. It’s a clever little repurposing effort for an old tablet, and after you get used to the tiny keyboard, it looks pretty darn useable. Head over to Node for the full guide.