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There have been several Raspberry Pi-powered mobile phone builds over the past few years (Tyler Spadgenske and David Hunt) but none have used the Pi Zero… until now. (Cue dramatic music).

Arsenijs from Latvia has created the ZeroPhone, and he reckons it has only cost around $50 to build! It can be used for making calls, sending SMS messages and has various text-based mini-apps pre-loaded. It runs Raspbian and pyLCI for the UI elements. The bill-of-materials is as follows:

• Pi Zero – easy to get despite people on Internet still telling otherwise (I got 5 by now). Let’s say it’s 5$ and 5$ for shipping.
• SIM800 modules – available in large quantities from eBay, 5$.
• ESP8266-12E used for WiFi (as per RPi-WiFi project) – 2$ from eBay
• Two-layer PCBs (two 4x10cm boards, one 4x6cm board) – can be ordered from your favourite fab or whatever people on Internet give good reviews about.
• ATMega328P – can be desoldered from an Arduino Pro Mini that’s typically 2$ on eBay, and it comes with a bootloader already! If you don’t have a heat gun, you can just buy a bare chip and burn a bootloader to it using a programmer.
• LCD screen – 5$ on eBay. Besides, a project like this can use other screen breakouts with similar characteristics (such as the ubiquitous Nokia displays) – it’s just a matter of writing a driver, which is easier than it sounds, and the front board accepts different display pinouts.
• Battery – you can use cell phone batteries, pouch and 18650 cells.
• TP4056 battery charger – modules are available from eBay, 1$.
• Buttons for keypad – 2$ from eBay (there are 3 types used, but you can omit one).
• 2.54 headers (both dual-row and single-row) – dirt cheap. Won’t be more than 0.50$ to have enough to assemble the phone.

It’s currently at working prototype stage and is, basically, a Pi Zero sandwiched between circuit boards. You can read more over on Hackaday.io.