I've made quite a pile of little LED lights.
I live off grid and my home is wired for 12 VDC. At first we used 12vdc fixtures but when 5mm white LEDs became available I started making home-made fixtures.
I have one neighbor on this mountain and naturally he is also off grid. He has been making LED fixtures for his home for a long time. Back in the day before white LEDs he used several different colors mixed in the same unit to sorta-almost approximate white light, and he has made piles of small LED lights and solar power units to light parks department out houses and boat launches at various camp grounds ( anyone ever ben to hawk creek campground on lake Roosevelt? ).
Anyway, for small units I just use bright 5mm white LEDs. I've purchased them in bulk from here -
And from radio shack for smaller projects. A very nice light for off grid cabin or car can be made by mounting six 5mm LEDs in a standard handy box cover. A toggle switch can be mounted on the side. Powered by 12vdc they make excellent reading lights by your bed or the like.
I once made a pile of such lights powered by two 9 volt batteries contained inside the handy box, and sold 'em at a gun show. They would burn a very long time indeed on those two batteries.
And of course, I've made a pocket flashlight by cutting the top off of an old 9 volt battery and mounting two 5 mm LEDs on it along with a small switch and two resistors, and potted the whole thing in epoxy. Snaps on top of a 9 volt battery, rather like the commercial "pack lights. Lots of fun!
Anyway, if anyone is interested in tinkering, this site will help you figure out your resistor circuits and is otherwise an excellent resource. -
Theses days my home is lit by white LED strip lights, with one remaining compact 12 vdc fluorescent fixture. I can light my entire cottage at about an amp and a half!
Edit - Yes, there are other ways to drive LEDs than resistor networks, but when you figure in the added cost, complexity and the tiny amount of electricity saved, I don't find it worth the bother.