How do you make netherite armor?

small thing to add - enchant the diamond pieces before you upgrade them, the enchantments carry straight over when you put them through the smithing table. and every piece eats its own template, so a full set means four. you duplicate them with seven diamonds and a block of netherrack around the template, which gives you two back.

you need ancient debris from the nether, usually around y -16. smelt it into scrap, four scrap plus four gold ingots makes an ingot. the bit that catches everyone now is the smithing template - since 1.20 you also need a netherite upgrade template from a bastion, and without it the smithing table just won't take the combination. you can copy a template with diamonds and netherrack once you have one.