Using what’s called a Peltier plate, an object that gets extremely cold on one side, while extremely hot on the other, you can build your own, personal heating/cooling device. It’s simple to make, and all fits comfortably in a project box. The author of this tutorial used a transformer, then plugged it into the wall, making it non-portable. However, you can probably get away with using 2 9v batteries to power the fans and peltier. Note, most peltier plates require 12 volts. Below is a picture of the controls as well as the heatsink needed to dissapate heat when you desire air conditioning. Read.
From the tutorial: “Down here in Arizona, we’ve got some pretty hot summers, at around 120 degrees. And inside, it gets up to about 88, which is a bit hot for my taste, especially when I’ve got my computer on – then it’s even worse. Or, if you live somewhere cold and wish your room was warmer at night, just flip a switch and your wish will be granted with this air cooling and heating machine.”