This is a reimplementation in KiCad of Don Froula's (http://projectmf.org/) PIC-based bluebox. The circuit was by Don Froula and the board layout was by Phil Lapsley (http://explodingthephone.com). It is so named because of Don's production of a close replica to the bluebox pictured in the October 1971 Esquire article "Secrets of the Little Blue Box." This version is based upon the ATtiny85 microcontroller.
There are three branches in this repository. Branch 'v1' is as close a duplicate of the original board as I can manage. As is, this board forms its own lid for the Radio Shack 230-1801 enclosure. The 'v2' branch is modified such that it can fit in the bottom of the Radio Shack enclosure. That one is probably a better choice for replicating Don's replica. The master branch has been modified to fit a Hammond 1591XXM dimensions 3.3" x 2.2" or 85mm x 56mm) enclosure, which I feel is of much better quality and utility.
This board requires six volts DC. Two or four CR2032 coin cells can be mounted in onboard holders or six volts applied to an external power header. Keystone 103 holds one cell each. Keystone 1026 and MPD BH800S hold two cells each stacked. I chose to try the MPD BH800S because I was uncertain if the Keystone 1026 would fit within the confines of the case.
Instructions: https://661.org/proj/bluebox/ (archived)