Commands:
/armortrimedit

Permissions:
armortrimedit.add (add armor trims)
armortrimedit.remove (remove armor trims)
armortrimedit.edit (add and remove armor trims)

Usage:
Hold a piece of armor in your hand and enter the command /armortrimedit. A GUI will open where you have to select a template and a dye material. Then click on the pickaxe item and the armor in your hand will be decorated with the selected materials. To remove the armor trim, click on the barrier item.