This ELT panel was based on a unit removed from a Bell 212. Although I primarily designed this for the Cessna cockpit, it is used on many different types of aircraft.
 
The panel is constructed from 3mm Acyrilic, and the support structure is 3D printed. The unit can be bought in several parts or as a whole unit.
 
A red 3mm led and red rocker switch is required for the DIY build. 
 
 
Measuring 35mm wide and 53mm in height. 
The Panel cutout Template and dimensions can be found here
 
The unit can be backlit if required.