I couldn't find a neon lights mod for the 1.12.2, so i decided to make mine in MCreator.
At first, it was only a few blocks, but now it's a full mod with mobs, guns, and of course pretty neon lights.
Current version:
Blue neon block
Red neon block
Green neon block
Yellow neon block
Purple neon block
Black neon blok, X and Y variants.
Yellow, Green, Red and blue Neo Soldiers. The only way to get Neon Weapons.
Violet Scourge. Tougher than the usual Neo Soldiers, and the only way to get the Plasma Blaster and (currently) plasma
Plasma Gun, using Plasma as ammo
Light gun and particicle handgun, with infinite ammo until they brake (something like plasma guns in halo)
Neo dagger and Neon Blade, for close combat fans
Dark Iron, a metal that can be used to craft weapons
The main star, the Neon mineral. Used for basically every crafting.