Amdek PHK-100 Phaser
The Amdek series of pedals was produced by Boss in the 80's as a DIY approach to pedals. They were sold as kits and generally used original Boss circuits. The PCB's came assembled and the buyer simply soldered the hardware and screwed the pedal into place.
The PHK-100 shares a similar topography and tone to the Boss PH-1r of the same era.