I am making a scripted projectile that flies through the air. While the script is working fine, I have no mesh for the particle itself. Ideally, this particle must be invisible, but can have a magic effect shader applied to it, so that whilst using the same base script for moving it, I could make several different spells/whatever by applying different shaders to it (eg blue or orange fire, or lightning or whatever). Also, the mesh ideally shouldn't have any collision so that it won't activate the trigger zones which I am using to get the projectile to bounce off things.

(Edit: Oh and ideally it would also have an editor marker so that I can see it in the CS )

If someone would be so kind as to either tell me how to make one using blender and my (very very very) basic skills in nifskope, or make one for me that would be fantastic (credit of course will be given in the final mod)

just get someone to export simple box for you. that's all you'd need. remove the texturing property and it shouldbe be invisible in game. the same object can act as the editor marker. in fact why no just take one of the editor marker nifs that ship with the game. You can just resize it in nifskope.