I know. These have been a little over-done as of late online, but I couldn't resist. Sun jars are little more than the innards of solar lawn lamps hacked into frosted jars to sit on your patio. Lifehacker posted a step by step guide, and for $8 a piece, it was hard to disagree that they'd look pretty sweet on my window sill or patio. The lamps are $5 at Lowes, and I got the jars for $3 at Cost Plus. The jars were the only size Cost Plus had, and according to the sheet the smallest size, marked "1/2L." I'd say smaller is definitely better for the jars; they're totally cute.
The one thing I did change from their guide was in the method of frosting the glass. They have you buy a can of glass frosting (like for Christmas), and spray it on, but I just so happen to have a mother-loving sandblaster, so I unleashed a pneumatic can of awesome instead. Getting an even coat was a little tedious, but it's a very stable frosting, so the effort was worth it. Other options would be to acid etch it, or fill the jar with marbles, broken glass, etc.
I also happen to have access to theater gels, so I've been debating whether to change the colors, but I've been *very* happy with white. My family loves them, and we're almost temped to just put larger rechargeable batteries in them, because we enjoy them inside in the dinning room.