Based on Emmett's ever popular gear heart: http://www.thingiverse.com/thing:12208
This version is about half the width of the original (50 mm), which means its 1/8 the volume and a much faster print (yay math!). i find it takes me ~2 hours to print one (and ~8 for the original)
Rather than just being a straight scaling, this version has been tweaked so taht it will still rotate. The main differences are the number of gear teeth (much fewer, and larger), gear ratio (it now takes 2 rotations to realign, unfortunately) and pins (made much beefier, and they are all one length).
Additionally, there is a hole through the tip so that it can serve as a keychain! Print them out by the dozen and give them to friends/family/cute girls on the bus!
== Edit 6/10/2012 ==
Added a zip of the source plus .stls for every individual component.
Added a "full plate" that prints all the gears + center. Left the pins out, since you usually want to print those with different settings. Fits on a replicator (not sure about others...)
== Edit 6/16/2012 ==
Added a chain connector to gear1 (the top). Updated the src rar (and fixed a compilation bug).
== Edit 6/19/2012 ==
Fixed the length of the pins. Shorted now, so gears should be less wobbly.
Print the two gear plates, the center, and the pins.
I've included the a zip of stls for each individual gear as well, along with the modified source openscad file.
I used a raft with .2 layer height, 10% infill and 50mm/s feed rate for the two plates. The center prints fine without a raft.
The pins are the key to getting the damn thing to actually rotate. Use a "multiply" profile to print the 8 pins necessary. I actually usually print 10 in a go, since usually one or two will have some flaw that makes it too loose to work correctly. The best settings I've found is to use a .3 mm layer height and 100% infill.
Then, just make sure you do a quick sand of the gears where they contact the center, and trim off any little protrusions that may be on the gear teeth (these can cause the gears to skip).
The largegearplate and fullplate have the keychain hole on the 8th (bottom) gear. You can separately print "keychaingear1" if you want the keychain connector up top