This 'lamp shade' was made by removing the bottom of the jar with a diamond cutter wheel on my Dremal then cutting a hole in the lid for the light fitting.
Cutting the glass was quite straight forward but you do need to take care. If you want to do this you MUST wear safety glasses. Tiny slithers of glass flying into your face remind you how delicate your eyes are.
I bought a diamond cutting set for about £5 for an independant DIY shop (the best places for this sort of thing). I wrapped some gaffer tape around the jar first to prevent shattering and provide a nice guide line.
A couple of passes with the diamond cutter and the bottom just falls of. Easy!
I then smoothed the edge down with an abrasive drum.
Then a final sanding by hand with some fine grit paper. All done.
I have made two lamp shades for the hallway at home and a pen jar for my desk at work. I'm now thinking of what else can give these jars a life after Dolmio.