- you need to set up a projectile spawn system (you can find some tutorials about that on youtube)
- Now there are two ways to do that:
-particle -> when you download UDK (unreal engine 3) you can find a cool particle system which looks like a laser projectile. Just open it and recreate it in the UE4
-mesh -> just create a capsule mesh and a suitabel texture (e.g a line painted in photoshop or something else that looks like that). Now create a material with the texture, give it a colour and connect it with diffuse. After that add a multiply - connect it with the diffuse texture and add a constant vector to the 2nd link - connect it with emissive and choose a value for the constant vector (how shiny it will be) 