Light fits below the existing end light, kept in place using the bolt that holds the end light glass.

Printing:
Print the casing with back side on the plate. It has integrated support that easily removes after print.
Print the glass also with the back side on the plate. 

Installation:
It fits standard 5mm LED, the glass snaps into place with pliers.
Its possible to upen it up again by sticking small hex wrench through the cable hole pressing against the diode/glass and the glass pops out.
There is a cable route, cables can be routed out on the back of the case. 

Happy printing!