use a palm sander and dremel.

 

I've been using a dremel with 3" circular sanding discs. I swear some of those lines never come out. LOL

 

The secret to making your plenum or other parts look like glass isn't just the products you use but a very high speed buffer with the right wheels. I don't believe this could be accomplished using just a Dremel. I polished my Nismo differential cover using sandpaper then steel wool and my Dremel with Mothers polish then I clear coated. Sadly you can't even see the polished area standing on your head.... But I know what it looks like!
Gary

 

The link is not working when I click on it.

 

I started w/ 400. Then 600, 800, 1000, and finished it off w/ 2000. Took me a long time to do this by hand.

 

Sanding the casting marks out with my dual action still took forever. 9/10 would not do again.

 

Anyone has any pics of what this is supposed to look like? the ones posted before just won't upload at all. Thanks.