Make your good old Thing-O-Matic truly automatic! Here is mine at the Seattle Mini Makerfaire last weekend churning out bracelets: http://www.youtube.com/watch?v=nmmUECyz-ek
Both of my machines printed continuously both days without any major breakdowns, my TOM giving away ~70 bracelets and my Rep1 ~60 bearings.

Since switching to PLA, I hadn't been using my Automated Build Platform, since it doesn't stick so well to the old kapton belt. However, I finally went through and fixed up the design, and it now works better than ever.

First, take a look at the ancestor, Truly Automatic Thing-O-Matic. Those instructions still apply. I've included a sturdier version of gaerisl's belt tensioner because my old one was warping pretty badly under the strain of keeping the belt taught. It requires a couple of M3x20 screws and nuts, but it goes on the same way.

To make the belt, cover a piece of paper (I use the cover of a magazine, because it's thin, strong and long enough for the belt) with kapton tape on both sides (to make it tough). Then cover one side with blue tape (blue tape sticks better to kapton than anything else). Then cut the belt out of this tape-paper, using the original belt shape as a template.

Print out the belt mould (I use zero infill with 4 perimeters for strength). Then wrap the belt around the mould and tape the seam with 3/4" kapton tape. Make sure the belt is uniformly tight so that it's a true cylinder. There will be a small gap you tape over (~3mm). Slide the belt off the mould and tape the inside of the gap as well. Fold the tape over the sides to make sure it won't peel.

Assemble everything as with the previous version's instructions and tighten up the belt until it rides flat. I find that even though PLA doesn't stick as well to kapton, it will usually still work even if the seam is under the print, since it's narrow.

I set the heated bed to 35C, mostly because it does something to the blue tape glue that makes it adhere to the kapton really well. This belt won't resist parts warping, so I recommend switching out to the heated build platform for more precise prints (hence the swappable build plate mod is extremely useful).