1 I wonder if it uses compressed air to push the foil around?

2 If you haven't seen it, you might enjoy the Discovery Channel/Science Channel series How It's Made. While they don't cover the machines that wrap peanut butter cups (at least, they haven't yet), they show how just how all sorts of items are made. If you don't have those channels, many of the vids are available on YouTube.

3

I had been dating this girl in high school for a couple weeks and she decided it was time I met the family.  Her Dad turned out to be a manufacturing engineer and was currently working on a machine that would make the grates for an air conditioner.  We hit it off immediately and I ended up spending most of the evening in his home office going over blueprints and getting the short course in How They Do It.  It was great and really illuminating.  As Steven says, I hadn't really given it much thought before.

The girl?  She was pissed, called me a dork, and that was the end of that.  Ah, well.

As to the Reese's, based on what I've seen on "How It's Made," my guess would be a series of simple arms would do the folding and then a ultrasonic welder or hot glue would seal the package.

4 Something I'd like to do sometime would be to take a simple object, like a pencil or something, and detail the entire construction sequence, as done in modern times (i.e., not the minimal sequence but the real sequence), and put it into a web page. Or it would make a good book.

I don't think very many people fully appreciate how interconnected the economy is; this might help. The most humble piece of modern detritus has hundreds of hands in on it before it gets to you.

5

If you actually went back all the way to the raw sources for things like the rubber eraser, the metal clip that attaches it to the pencil, and the yellow and black paint on it, plus the binder used to hold the graphite together, it would be a really deep dependency tree even for something as simple as a pencil.

As for a pen, well! Then you have to go into the manufacturing process for a couple kinds of plastic, plus maybe four kinds of metal, not to mention all the stuff that goes into the ink.

6 "Something I'd like to do sometime would be to take a simple object, like a pencil or something, and detail the entire construction sequence...it would make a good book."

My three favorite manufacturing process stumpers:

1. How do they roll gunpowder into firecrackers?
They don't. They roll up long tubes on a thin stick, pull the stick out, cut the tube into firecracker-sized chunks, bundle 'em up into a hexagon about 18" across, crimp the ends on one side with a fist full of pointy sticks, paste a sheet of paper over the other side, pierce the paper over the tubes with the pointy sticks, then sweep a handful of powder over the paper so it falls into the tubes. The fuses are inserted, and the pointy sticks used again to crimp the tubes shut. At least, that's the way they did it, by hand, at incredible speed, in the grainy, black and white film I saw at the '76 bicentennial PGI convention. The workers were barefoot, seated in a dirt-floor shop. Mass-production is not necessarily high tech. There probably is a machine that does it now.

2. How do they make aluminum foil? "Duh. Squeeze it between rollers." Duh, except no matter how much pressure you put on two steel rollers, the aluminum bounces back to about twice the desired thickness. (Hint: The foil is shiny on one side, dull on the other.)
They put two sheets through the roller at a time.

3. How do they make that undulating "egg crate" foam sheet used for shipping and acoustic control? This product often appears as two matching sheets; a close examination shows that individual bubbles at the surfaces are cut in half, so some kind of curvy knife must be used--right?
A flat sheet is squeezed between undulating rollers, and a straight blade slits the sheet before the sheet can re-expand on the other side.(A similar trick is used to make foam clothing dummies, as revealed on a recent episode of the above mentioned "How It's Made" TV show, which is indeed fascinating.)

7 Aluminum foil (and wax paper, which all the Resses' cups I've seen are wrapped in) are pretty heat-resistant. They probably just lay the foil over the crinkled cups that they'll eventually pour the chocolate and peanut butter into, and then press it into shape with matching key forms. Then they pour hot chocolate into the cups, drop chilled peanut butter wafers into the middle, and pour some more chocolate over the top to cover the peanut butter completely. Once the chocolate hardens, the foil is cut and wrapped over the top by another machines.

Well, at least, that's how I would do it.

8

Refugee, I know the answer to your #3, and it's clever as hell. The cutting is done with a straight nichrome wire, right?

As to #1, I always assumed they did the rolling first, then put the gunpowder in and folded the ends to seal it. (I'm writing that without looking at your spoiler.)

9 Tatterdemalian, it's that last "wrapped over the top" part that I was curious about.

10 Right on three, although I think I've also seen it done with an actual blade.

I always assumed firecrackers were rolled like cigarettes, but no. The real question is, how is it done efficiently?