Creating Trails ( 3 Dimensional / Animation possible? Also, max size? )

[Fscreams]

I know how to create trails, but does anyone know how to actually get it to be 3D like the smoke trail or tube trail?

What's the maximum size ( pixels ) you can use to create a trail, I do 128 x 128.

[Rubat]

Those are not 3D. Just open one of the trail textures and see all you need to see. ( They are in the .vpk of GMod and source engine )