Well, believe it or not, someone has elongated the idea of heat sinks by attaching more heat-aborbing household materials such as pennies and paper clips.
Great idea, you can check out the DIY page here.
All of the pennies are 1981 or earlier vintage, that being the last year US pennies were made mostly of copper. After that, they’re mostly zinc, with some copper plating. The pennies in configurations 2, 5, and 6 are all 1981 pennies made in the same mint. I didn’t feel a great need to find identical pennies for configuration 4.