I was wondering if it would be possible to make arms for a NEMA or lightweight cobra head from metal conduit? You could bend it to match a certain brand or style of arm and then weld on a plate for the bolts and maybe add a through bolt bracket. You could even add a decorative scroll to make it look like an antique arm.

I'm thinking it would be cheaper than getting a real arm, and easier to find, since lights seem easier to get than the arms.

The only thing is I'm not sure how sturdy it would be.

I wouldn't trust EMT conduit with any kind of significant weight . something like a NEMA , yes. anything else, NO !

 The thicker, rigid steel type might work but I would still keep the arm length rather short.