The shaders are connected to a specific forge. You can’t run the same forges every week and expect to give them all. The green shader drops at volundr. The red shader drops at gofannon. The blue shader drops at izanami. The purple shader drops from getting a masterworked curated weapon from either a weapon frame or scourge of the past. The refurbished shader is from dismantling any black armory prototype weapon, though be warned. It’s a very low chance you’ll receive if. For the forge specific shaders (other then the purple one), your best bet I’m getting them is to buy the item from ada-1 that guarantees an armor piece on a forge completion. It’s faster and mor likely you’ll get a piece with a shader. The rest of the shaders are purely just luck whether you get them or not. Scourge is a very good option to get the purple shader, as continuously playing it with moments of triumph going on will eventually get you a curated weapon with the shader. Refurbished is the real difficult one. Try to get maximum temper on the forges. It increases the chance the forge will drop a black armory prototype weapon like galliard. You will most likely though have to go through hundreds of forge completions and weapon dismantles to get it, as the drop rate from dismantling is quite low.