Cooking with the Sun
A solar cooker is a fundamental nerdy DIY project. Ditch the microwave or range. Cook using just the sun's rays instead! Yet many people bypass this incredibly useful tool because they think it's too hard to create.
It's easy to build your own solar cooker with household items, and you can use one of dozens of different (and free) plans that you find online. All of them use the same principles to heat food or beverages.
You're simply concentrating the sun's rays with a reflective material, such as foil or metal, toward a non-reflective (read: black) container that soaks up the light and helps turn it into heat. Cover the contraption with clear glass or plastic to trap heat and reduce heat loss to typical outdoors breezes ... and then wait.
Depending on the type of food you're cooking and the amount of sunlight available, it might take you half an hour or several hours to complete a particular dish. Once you're done, though, you'll literally be able to eat the results of your nerdy endeavor.