My wife has a Targus Chillmat. Love the design, the cooling is virtually nonexistant. It uses two weak 80mm fans and is basically unmoddable due to fused plastic holding everything together.
Money really isn't an issue. If money were ever an issue I doubt many people would hack and mod anything.

I'm not doing this to save money or anything; I'm doing it because I have identified a need that no product currently addresses: Significant cooling for lap top computing in a lightweight form factor.
For the prototype, I used a venting pattern of .130 diameter holes with .250 spacing.

I have lots of other patterns but I want to see how this one works first. Alternatively I can cut a logo, words, or something fancy in the laser once I determine the best approach to venting for airflow while still mainting structural integrity. I don't want the whole unit to bow in the middle under weight of the laptop. There is also the option of bumping up to a thicker gauge aluminum although I'd like to keep it at 0.060 so the unit stays very light.
I did make holes for 140mm fans. In the next prototype, I will most likely provide various hole spacing for 140, 120, and 80mm fan configurations.
I ordered my parts and they should be here this week. I'm going to have the shop guys run the metal under the timesaver and then form the unit today.
For fans I went with two Noiseblocker PK1s. With a 9dBA rating, these things should be silent. I also like how they come with silicone gaskets, short and long cord extensions, and rubber fasteners.
The fans will be mounted and then connected to a LianLi PT-FN03 PCI fan controller. The fan controller will be mounted on two tabs on the right side of the unit which is not visibile in my picture above. This unit also gives me the option of going with 3 fans.
Lastly, the unit will be powered by an external 110v AC to DC 12V power adapter with molex connector. I wanted to avoid external power units but USB power just isn't a viable option for considerable cooling. I also didn't want to mess with drawing too much power or screwing with the electronics of things that are plugged into my brand new laptop. The good news is that with a 6 foot wall to brick extension, I can mount the brick inside the back of the laptop cooler so the only thing needed to plug in is the cord from the wall to the brick.
I'm interested to see how it all works and what types of temperatures result. I have no doubt a second or third interation will look much much different. My primary goal was to create a unit that would provide more cooling than anything else out there that is for true lap top (as in, on your lap...not a laptop computer) gaming. First I wanted to get the cooling system sorted out. On my next prototype I will focus on the ergonomics, non slip materials, perhaps a USB hub, and the aesthetics of the thing. I do know that I want to keep the general design the same, as I personally think the Targus Chillmat is the best design for lap top computing. It just, well frankly, it sucks when it comes to cooling. Fine for a 15" business laptop but severely lacking for a 17" gaming rig.
Hopefully I'll have everything assembled and can provide pictures by this weekend.