I've tried to do it via datapack but cant figure out what im doing wrong.
This zip is the datapack i tried to make...
mythicmetalstrims.zip
Heres the Trim gradients i put in a texture pack.
Mythic Metals Trim Colors.zip
I think it would be better to have the materials natively supported anyway but I'm willing to continue the data pack route once i get over this cold.

Trim Materials is something that is planned in the future. Mainly I want a curated set of materials to be used, instead of all the materials in the mod. This is because of duplicate colors, I.E. Adamanite and Redstone being similar, and/or Palladium and Resin being almost the exact same color (thanks mojang).

Since I am undergoing texture overhauls at the minute it isn't something I am prioritizing, although out-of-the-box Mythic Metals should support custom trims from any mods, as proven with the attached video (shoutout to Bawnorton for AllTheTrims support).

<noaaan> does it add all the trims to the registry?
<me> yeah
<noaaan> mythic metals has a command to summon every armour set with each trim material and pattern
<me> runs it
<game> :dies: