At first I was a little intimidated by the rainbow thing, so I had a peek at Poseidon's textures and it turns out all you do is make the diffuse and the control rainbow coloured. WHO WOULD HAVE THOUGHT.
So I present to you Cazy's latest Agnetha hair retextured in 3 different ways! I'd like to thank Chedderprime for giving me the link. <:
Teen-elder has all 3 versions, and child and toddler only have shine (if there is enough demand I will add rainbow and streaks for the young'uns--right now I'm far too lazy...despite the fact it only takes 5 minutes, max. <<<:).
I will be going back to Cazy's Revival and a few of my other retextures to add streaks/rainbow versions as well, so keep an eye out for those!
The rainbow version isn't fully re-colourable, however you can make some cool effects by dinking around with the tips, etc. Mesh included and you can have all versions in your game at the same time.
PLEASE READ: In order to get the best rainbow colour, make sure you Sim's hair pallet colour is set to something light--like blonde.
Download here. Toddler, child and adult (streaks, rainbow, shine) are all included in the zip. It's about 17-20MB, compressed. Forgot add...for those of you who want the files downloadable separately as it is a rather huge file, let me know and I'll put those up.