I had 6mm MDF scrap in my garage and I didn't feel like going to the hardware store to get a 3mm (?1/8") sheet, so I modified 300dpi's Laptop/Tablet Stand to work with 6mm (?1/4") MDF. I have simplified the design to only include what you need to make one stand; not a separate stand for the laptop and tablet. I have also removed some of the additional notches on the spacers. This should be able to support most laptops up to 15".
Lasercut Waffle Structure Laptop Stand. Easy to use press-fit connections. Feel free to use it as you wish! It works great! I made it for my wife, whose laptop overheats whenever using photoshop or rendering an image. The design is based on being as open as possible to allow air to freely pass through on all sides and optimally cool down the device. Test it out for your self if you have access to a laser or cnc router. More variants can be found at http://www.lasercuttinglab.com