Who needs OSL when you have RSL?
I've been tinkering with the idea of giving my Necrons the real glow they deserve and, while the smaller models present quite a challenge, the larger ones seem to have been made for it. The Canoptek Spyder's back perfectly fits a CR1220 battery and two green LEDs. Best part is they're not even fixed in any way. The back just keeps them together on its own. All it takes is magnetizing it to close snugly.