I was asked by a customer to make a headlight insert for an Atlas RS 1 shell he wanted to convert to a different railroad. He needed a insert with two independent lights side by side. Well needless to say I like to tinker around at nearly impossible stuff.
The diameter of the insert is 2 mm, with two 0.6 mm openings for the lights. 3D printed in grey resin. Additional I made the lightblocks, which fit snugg into the insert on one side and the hole in the shell on the other. They are also 3D printed in clear resin.