I’ve been making good progress with my pirate wifi project, Occupy.here. This is how my current prototype looks, built from a TP-Link TL-WR703N. This is the Chinese-language version of a similar router, the TL-MR3020, it’s just slightly cheaper. Once you install OpenWrt on them, the two models are essentially identical. It’s powered using a portable battery that provides a 5V charge over USB.
Note: Amazon links will result in me getting a small kickback