Glowing texture for projectiles, is it possible?

You (probably) can't do this with MCreator, but you can do this pretty easily with Optifine, using either a resource pack, or by using optifine-compatible textures in your workspace.

Optifine has a pretty basic emissive tool that allows you to overlay emissive textures, (textures that glow/retain their brightness level regardless of light), onto blocks, items, and entities. You would need to:

• Add an 'optifine' folder your mod's src resources. (You need to look in your MCreator workspace folder, go to src, and eventually get to the part where it keeps the textures. You can basically download and look at any optifine-copatible resource pack to see what the file structure should look like.)
• In the folder, add an 'emissive' property file. (This is the file that will tell optifine which textures are supposed to be emissive. Most resource packs just use the '_e' suffix. Again, you can basically just download an optifine compatible resource pack, and copy-paste the emissive file.)
• Then, just make a glow texture, and make sure the texture has the same name as the projectile's original texture, but add an '_e' suffix, (or whatever you defined the emissive suffix to be. The name would go from 'my_projectile.png' to 'my_projectile_e.png.) If the glow texture is identical to the projectile's original texture, the entire projectile will glow, but you can also just make sections of it glow, depending on how you design the texture.

Best of all, optifine compatible emissives will also be compatible with shaders! MCreator does let you add built in glow textures to most other entities, (I'm not sure if there's a built in system for glowing blocks and items, which might explain why Optifine handles it) so it's kind of odd that projectiles are an exception. I wouldn't be surprised if support for this was added in the future. 

Oh, and just keep in mind you need to have Optifine extracted and installed for this to work. There's probably a way to install it in the developer client, but it might just be easier to run it on your own version of minecraft for testing purposes.

im pretty sure its possible locking the code; the item can use a 3D model, its a block model so there is no reason it cant be emissive/glow, mcreator just dont have a checkbox for it.

You could also probably do this with an optifine emissive texture, either with an external resource pack, or just built into your mod's src file.