Text on Models

I need to create and effect like on halo, where by, when you fire your weapon the bullet Meyer on the weapon de tease. How would I do this? I'm using unity4android so having 32 textures and loading them in the ram is not possible.

Another way I thought about was like dead space hologram and have the 3d text. But the 3d text appears through walls which is bad.

Thanks for any replies!