More ideas like this are featured in a free downloadeble ebook on my website www.ruudvankoningsbrugge.nl/flessenboek
sorry this is in dutch, but the google translator works wonders. Eehhh, yeah, wondrous wonders most of the time. The pictures and drawings are no problem for anyone.
Step 1: All Parts
an emty detergent bottle
a simple lampstand ( i bought one cheap in a house deco shop)
a bottlecap of a other bottle ( The top should fit snug inside the rim of the bottle)
small ring of bicycle innertube
A sharp knife
Step 2: The Connection Bit
Step 3: The Fitting
Step 4: Reshape the Bottle
Place the bottle over the rim on the socket. I had the luck it fitted perfect but you could use some ( doublesided) tape to make it fit.
I covered the screw-thread of the bottle with an elastic band cut from a bicycle tyre.