This workshop premiers the world's first £20 brain-smartphone interface, and describes the theory behind it (especially SSVEP). This is v0.1: we finished soldering the boards on Thursday; we don't know how well they work; the code (currently only for Android) continues to be developed as of Friday. The workshop's goal is to open the project to a larger community, spurring further development. At worst, you'll get to walk around wearing tin foil, a bathing cap and electrodes; at best, you'll be able to identify various EEG signals on your phone. If you can, please bring a POCKET KNIFE and a SMALL SCREWDRIVER. See http://bit.ly/2axdWku for hardware, software, etc. (Colin and his sons have run Google Cardboard workshops at EMF 2014, CCC 2015, Tokyo Hackerspace, the Okinawa Institute of Science and Technology and Maker Festival Toronto).