Hi there!
Here's the problem; many of the really nice fantasy outfits that fit the Project Regalia avatar use Omega appliers for the 'shirt' that goes between you and the armor/outfit. And the Project Regalia avatar simply isn't compatible with Omega stuff.
So, to help out all of my fellow fantasy mages or anyone else who just really likes fantasy outfits, I created a set of appropriate BoMR tattoos in a dozen colors: doeskin, dirty, green, blue, black, leather, tan, rose, red, purple, teal, and white.
And they're all included in the same box!
To use these you will need a current viewer for Bake On Mesh functionality, and the BoMR applier here:
https://marketplace.secondlife.com/p/o-Bakes-on-Mesh-Regalia-BoMR-Applier/18397648
(It's free, don't panic!)
Once you've set up your base skin, simply adding or removing the various tattoos will add or remove the chainmail tops - easy peasy!