So I was able to do THIS!
The original tutorial was only slightly different- She painted the fixture, which I didn't need to do for this one, and used a series of nail punches for the lid, while I am impatient and used a box cutter.
So here's the beginning fixture-
The concept (That I couldn't figure out) is to basically just cut a hole in the lid just big enough to go over the existing bulb port.
Its easier to do it on the jar, like this:
And I know its scraggly but it doesn't really matter, as long as it goes over the bulb port BUT it's small enough to stay in place with the screw-on holder (My explanation sucks, good thing you have a good DIY link with better directions above ^)
It took a little twisting and arranging to get it straight
But then it was perfect!! And I couldn't believe what a fast project it ended up being!
(this is the picture I sent to my bff after installation)
So thats one project down, a bunch more to go! (Like framing that mirror, apparently)
I hope they're all that easy and cheap! 15 minutes (not including time admiring it) and $6 for the jars.
By the time mason jar lighting is not cool anymore, I'm sure there will be something even cooler to replace it with. And I will figure out how!