Amazing idea, I have some idea around insulation, can we work on this? together

awesome project, a lot of people do need this. Especially in hot countries like mine.

You could make the heatsink tubular, copper and run it parallel to the glass vile, have the fan blow _through_ the tube heatsink

Larger mass, area, and better use of the fan! Possibly easier to integrate to the case as all you need are to holes.

I like the idea of the copper pipe, but actually for the cold side! It could surround the pen and more evenly distribute the heat absorption and make cooling easier.

On the hot side, it might be worth looking into. But there is also the factor of having the pins on my current copper heat sinks. The tube may have more surface area, but not able to shed the heat as well. This small fan may not be up to the challenge of cooling the heat sinks anyway, more testing required. 

Thanks for your suggestion.

puncture the tube inwards, to create air resistance like a  cheese grate... like heat sink wrapped into itself.... or Screw bolts into the tube radially inward....basically create the heat sink pins inward.

I like your extension of the idea to the cold side! that would be better indeed!

cool project, peltiers have always fascinated me!

I think the one important aspect you are missing in your current iteration (unless I'm missing something) is proper insulation, of which the battery life will evetually depend. 

also, is the yellow part some kind of a fan? I didn't know they made them so tiny

Yeah insulation is something I will have to look into also. Right now to test the design, this case only costs about $20 from Shapeways, which is awesome. I'm thinking that on the assembled case a nice rubber sleeve or cover could do good things for insulation. I'm also thinking that some thermal mass like a chunk of aluminum on the cold side surrounding the pen would help also. 

And yes, that fan is real... I love small electronics, and when I found them I ordered a couple. This will be the first project that I will use them for something. Really excited. The one in the CAD drawing is 15mm square, but I also have an 8mm one. Check out this picture I took on my Instagram. 

https://instagram.com/p/x72CyiQ--3/?taken-by=idlehandsdev

that is awesome!

also an observation: since the peltier heats up on the heatsink side, the whole case will likely heat up more on that side.

Very cool project Sean!  Cooling generally uses a lot of energy - but with such a small volume of liquid to keep cool, less "common" methods might work out - like pelter, etc. 

Thanks! Yes I need to experiment to see how much energy is actually
going to be required for what temperature. Most peltiers are designed to
have quite a large temperature differential from ambient. Since insulin
only needs to be kept around 2C  (generally ~20C Delta T) there should
hopefully be some energy savings in that regard as well. It could find
itself just being a plug in device if its too power hungry, but this
could still help many people who travel to hotels that don't have
fridges, or are on driving trips as they could plug the holder into the
vehicle.