I missed this the first time around, but apparently a site called qj.net posted a tutorial on how to make vinyl copies of vinyl records. Unbelievably, that site is no longer live, but this Mike guy went and dug it out of its digital crypt and re-posted it for all ye pirates to use to pirate your pirated vinyl.
This process — making a silicone mold from a record and then filling the mold with plastic — would probably come in handy if you had some real rare record that made you want to have your cake and eat it too — i.e., sell the record for mucho dinero on eBay and still have it on vinyl at home. Of course, that would mean pouring silicone over your precious, precious extra-clean, NM+, only-played-twice record, which I think a lot of collector geeks and eBay dilletantrepreneurs would not want to do.
One hitch here is that you can only make a copy of one side, and the other question, of course, is what about the quality of the copy? I'm no plastics expert, but I suspect the vinyl used at a real record pressing plant is better suited to making records than off-the-shelf casting compound. But I could be wrong.
Of course, you could download hundreds of albums in the six hours it takes the silicone mold to dry, so the real deterrent here is effort, which is more than the approximately zero effort it takes to UnRar an archive or plug in your friend's external hard drive.