So far I've had good luck with getting very useable replacement parts-Chinese, of course-for my 034's and 066mag at a big discount even to used OEM Stihl on fleecebay from seller HUTZL. Haven't tried any plastics yet but the new clutch cover for the 066 was $12.16 delivered, included a new dawg with 2 Torx screws with Loctite already applied, 1 nut for same and 2 bar nuts, so the cover was essentially free.
The casting quality is very good, dunno if it's actually magnesium or just aluminum-it's light enough to be Mg-it has the nylon friction-reducers [?] [remains to be seen how well they hold up] press-fitted and the black rubber bumper fitted over two pins at the rear of the cover.
NO casting flash anywhere and the paint quality is better than what came on my Ford Ranger. Only thing missing is the OEM NO: 1125 640 1701 in the casting itself, it's stuck on a paper label on the outside of the shrinkwrapping.