all real PKM receivers are "sheet metal".... if thats what ya mean... but its not a thin or flimsy. they are about as thick as you could ever want.
Pryotex's receivers are very good & easy to work with.
YES i was the test builder.. & there were some things i looked for that we can get into if you want more info..
adjustability, weldability, correct lengths, fits & so on.