Whew! This one took me a lot of time and thinking.  
Putting the particles toghether wasn’t easy, and if you take a close look, you’ll notice I missed one color in the rainbow.  
After 2 and a half hours working on this, I got kinda tired and forgot about it D:.  
No graphic alteration programs used, just plain Garry’s Mod and a large array of addons.  
I hope you like it despite it’s tiny flaws ^-
 
Edit: The trail looks a lot like the one in “The more you know” ( [link] ). Thanks to my friend Cold Snap for letting me know, it was a rather unexpected coincidence