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 made from 3mm acrylic for the back panel, which can be illuminated, although the real unit itself is not. The backplate features laser engraving for precise text. The ELT includes 2mm acrylic switch guards that fit snugly into the faceplate and can be securely held in place with a small amount of super glue.
 
A red 3mm LED and red rocker switch are required for the DIY build but are included in the complete unit.
 
 
Measuring 35mm wide and 53mm in height. 
The Panel cutout Template and dimensions can be found here