Awhile back I came across this item by IKEA. Originally designed to power up to a 75W bulb, it came with a large paper "shade." It looked ridiculous to me, so I left the shade and took only the power cord/socket/and hanging mounting stuff.
It has a polarized plug, but is not earth grounded. So I would be a bit dicey about using it outside unless protected against water, etc. The socket itself has a threaded plastic exterior and has another threaded attachment that spins on and off. So it could be mounted through a hole in a piece of plexi or somesuch.
Here is other hardware and pics of the shade and how it was designed to hook up.
I decided I have no use for it now, and thought one of you might. I sometimes say first come, first served, thought to do it a bit different now. Should there be interest, post your name and a number between one and ten. I will pick a # and the person who picked that one or closest will get it for postage. No need to post past ten.