How many times do you find yourself struggling to unlock the door in the night?well personally many times so I made this..
Or you can get something like this..http://www.lvsales.com/keylight.htm but were is the fun in that?

Step 1: Parts

First lets see the parts. I wanted a high brightness led so a button cell at 3volts 2025 or 2035 was not an option since the led is really dim and does not last long.So I went for a li-ion cell for more power.
http://cgi.ebay.com/Li-ion-Rechargeable-LiR2032-Coin-Cell-Battery-w-H-Tab-/160437617991?pt=US_Batteries&hash=item255ad3c547
CAUTION!!these are not protected so be very careful when charging! Then is the led, a white wide angle flat top one, a small switch recycled from some old gadget and lastly the key.

Step 2: Drilling

For 2 reasons I decided to make a hole for the switch. The first is that I did not want the key to become too thick. The second and most important is that if the button of the switch was way out,when I would cover it in shrink wrap, it would be very easily pressed witch means that it would light up even in my pocket.So I drilled a hole big enough.On the next step though, it was needed to make some adjustments to the shape of the hole after soldering the tabs.

Step 3: Electronics..

Some soldering..no resistor but I guess it should be on for a few seconds only at a time.Little tape over the battery and test fitting and almost done..

Step 4: Done..

Lastly some heat shrink over everything,testing and all done.. A better solution would be elasti dip http://www.oag.no/productdetails.php?product=65 but did not have any..