I primarily use a PC I built for gaming, so please bear with me when I say I have a MacBook lol.
But I do have a 2011 MacBook Pro (hopefully will upgrade next year lol). All I do to keep it running pretty cool is have it sit on a large, thin book. My 15" MacBook sits just about perfectly on this large Star Wars book I got when I was younger, and the book isn't too thick. This keeps it from being directly on my lap.
"Laptops" aren't really made to be on your lap as I'm sure we all know lol. When I worked for Apple, we weren't even allowed to call the MacBook a laptop, it always had to be a notebook. Just because they didn't want people thinking they should keep them directly on their laps (which I totally understand lol).