I have used these, and they work great. You need to know that they put out a very narrow beam of light, which is very effective for lighting individual props. Sometimes you need to use more than one on a prop. You can create some really neat lighting effects by lighting 1 side of a prop with 1 color and the other side with another color. 1 power supply can usually power a whole bunch of these at the same time. You can easily buy wire to extend the cords as needed. You just have to make sure you attach the positive to positive and the negative to negative, otherwise it won't light. It won't hurt it, it just won't light. As you probably know, LED stands for light-emitting diode. A diode is an electronic component that only allows electricity to flow in 1 direction. So if you reverse the polarity, it won't light because it is doing what it is designed to do... prevent electricity from flowng in the opposite direction.
Anyway, give them a shot, I think you'll like them. Just remember that they won't put out a lot of light. They are perfect for focused light on a single prop where you don't want light to bleed onto the ground or other props like a flood light will.
This is nothing more than a single LED and a resistor in a piece of 1/4 brass tubing that you can get at any hobby shop or craft store. You could easily make your own and using the right value resistor configure it to work on any voltage from 3 volts on up. As Xpendable said the beam is very narrow and I don't think one would come close to lighting up a prop outside unless it is something small like a skull laying on the ground. I would expect to use something like this in an indoor haunt to provide very dim lighting to see your way though a maze. A single led is not going to put out much light. Think of those single LED lights that you can get for your key chain. That is what it is going to be like.
Hallow and this is a really helpful thread for those of us that are just venturing into the LED scene. Creating little spots that focus on individual props is just what we need in our little haunted trail. Thanks for this thread!
For power you might want to use an old computer power supply. You will have all the 12VDC current you would need. (As well as 5 VDC) There is a step by step tutorial on Instructables - Make, How To, and DIY (sorry, not that much into computers to make the link thing work) I am in the process of converting one right now to use on my 3 axis skull. I got the power supply for free and am adding about $5.00 in parts. Just make sure you have it unplugged before working on it Hope this helps. K
I found some great little night lights from Lowes today. They have led bulbs and put a great low level light on my changing portraits. They have plugs so I used cheap extension cords to mount them on top of my portraits. They are $7 for a pack of 2. I glued blue colored gels over the light. Works great!!!!
Tap Plastics carries any color plastic you would need. If you used the light that Spookym suggested you could get 4 light for the price of 1. Also if the light is to wide of beam just get a piece of pvc and stick it over the end of the light. Then you will have a very narrow beam. You could adjust the beam by sliding the light back and forth in the pipe.