I currently use this material set-up:
I then use this material in a particle emitter and let it spawn one particle. This is what it looks like in the level using a directional light:
The volume is there, but it looks the same from every viewing angle, which is of course, the main problem.
Not sure how to progress. What I would need is an “extrusion”-like effect of the texture in the z-axis, so that its like a cylinder, if you know what I mean.