I live in New Mexico, most of our buildings are made out of Stucco or Adobe, or frame and board. So I was afraid we would run out of good ferris surfaces to "throwie"
Also figuring we would run out of magnets I stopped by the store for some fishing line, and hence the "snaggie" was invented, they work quite well on trees during the winter.
A snaggie is just an LED a battery a loop of fishing line and some tape (these are cheaper to make than throwies due to the lack of a magnet)
Step 1: Bend the LED legs
So i bend the legs into a JJ shape. (see photohttp://www.instructables.com/files/deriv/FJT/BVL2/FCHYNTP8/FJTBVL2FCHYNTP8.MEDIUM.jpg
Step 2: Affix the "snag", Tie a loop to the LED
Step 3: Put the led on the Battery
sometimes i will slip in a bit of wax paper (or in this case a bit of pastic backing from some velcro, so i can keep it off until i pull the tab)