Block of metal to help cool down metal-enclosed laptop I have a metal-enclosed laptop (HP Firefly G8).
It's kept up right by a laptop stand, closer to a 45° angle than this stock pic:

To help keep it cool, would resting a block of aluminum bar against it help? I found 1x2x8 inch bars on Amazon, which would cover nearly the full width of the bottom of the laptop, which faces up.
 A: If you place those bars next to a hot object, they will absorb heat only until the bars and the object reach the same temperature. This will take a while if there's a lot of mass in the bars, but the cooling effect will eventually stop.
Now the bars have to get rid of that heat. for ordinary temperatures, this occurs by conduction to the air next to the bars; its rate will be proportional to the surface area of the bars, through which the heat transfer occurs. as conduction cools off the bars, their temperature will drop and heat transfer between the object and the bars will continue- but at a rate now limited by heat transfer between the bars and the air.
This means that you want the bars to have the greatest possible surface area and so you put a lot of fins with lots of surface area onto the outer surfaces of the bars. Now you have a heat sink which can soak up the heat from the object and conduct it into the air.
But wait- there's more! now the fins are heating up the air, which becomes slightly less dense than the cooler air surrounding them. That warm air wants to rise, and if we dispose the fins vertically then the warm air will rise up to the tops of the fins and exit, while cooler air is drawn up into the spaces between the fins- a process called natural convection. This increases the heat transfer capacity of the bars.
However... a little fan with a motor on it is far more efficient at getting rid of heat from inside the computer case because it works on the principle of forced convection, which eliminates the need for bulky and expensive external heat sinks.
The switch turning the fan on and off has no moving parts so it never wears out and the fan motor uses very little energy compared to the CPU board inside the computer. As long as the inlet and outlet ports for the fan remain unobstructed, any extra cooling capacity than that is unnecessary.
