I think some different textures for some parts might be nice, I can't really explain it so I'll give an example instead.

Having the option of changing an ingot texture to metallic, non metallic, shiny, dusty, rusty, corroded etc. might be nice, like this.

Another example would be choosing a texture for the ores, like having a

• lapis style texture
• default texture(iron, redstone)
• emerald style texture
  etc.

Create different parttypes and give each parttype the default texture you eant ot to have (e.g. material.registerToParts(["ingot", "ingot_hot", "ingot_corroded"]);

Also, you can always override how a specific materialPart looks like.