Many of the home-depot conduit parts are zinc, so no good at all for this application. If you find them in steel, they should work well enough.
I made my own, 4130 tube welded to a base plate. The wires are wrapped with firesleeve tight enough that it is a job to get the sleeve inside the conduit. Then another firesleeve is on the outside of the conduit. a hose clamp holds it on the conduit and a stainless band clamp to the bundle.