The faceplate is designed and 3D printed to replace the stock one from a Kinter MA-100; a nice little all in one MP3 player (usb or SD card), Radio & AUX input unit.
In order to make sure the ammo tin remains water tight when closed, the AUX in, aerial and power have been relocated to the front and integrated into the faceplate.
There's also a simple little LM3914N 12v battery monitor circuit which drives the LED bar graph.
I used an old battery from a dead handy vac so the battery only lasts around 6 hours, there is a lot of space behind the speakers so I'll probably end up getting a couple of new 4Ah SLA's to replace the used 2.5Ah one in there now.
For those interested, the faceplate is available on Thingiverse.com