I made this motion detector for the purpose of having a cheap, easy way to put my props on a timer. It's set for 5 seconds, but could be set for 4 minutes or 12 minutes.
This requires some basic electrical knowledge. I have tried to keep it as simple as I can and believe any one can do this project.
When testing the final result, please keep safeguards in your immediate vicinity. Fire extinguisher, remove flammable materials and liquids, eye, ear and hand safety as well. It may be overkill for such a small project, but it is better to be safe than sorry!

Step 1: The Little Things...

I used an infrared motion detector and 6 plug surge protector I bought from a hardware store for about 25 dollars.
The tools I used were a Phillips screwdriver, needle nose pliers, metal tape (I believe its actual usage is for duct work for home furnaces), and scissors. Not pictured is soldering iron, solder, and a hacksaw.
No other tools or wire were required.

Step 2: Patience Is Key

The drawings I did was to give a basic idea of how the wires will be run between the sensor and the surge protector.
Take the surge protector apart in 3 pieces. Mine was a metal surge protector but there are many different types, all should hold to the same principal design.
I cut off the wires to the switch, except for the white wire. The yellow on the drawing represents the white wire (didn't have a white marker, it'll happen). The black wire from the sensor I hooked directly to the black wire on the S.P. and tied it together with a wire nut. And as you can see from the drawing how I did the rest of the wires. Be sure that the solder holds the wires properly!
In order to make it one piece, while it was apart, I used a hacksaw to cut a notch out of the case of the S.P. and cut off one plug from the end. I put a hole in the bottom. The motion sensor is fairly big, so I went through the bottom so as to allow more use of the available plugs on the top side.
Putting it back together be careful so that none of the wires become pinched or cross into other metal parts and don't forget to reattach the green wire to the case! (On mine its green, I'm pretty sure they should all be the same in America).

Step 3: Set and Test

To seal it up better, and to make it look a little better, I used the Metal tape to finish it up.
The sensor has a 180° view, so it has a wide "eye" for what's around. On the bottom of the sensor, put the switch to "test".
After you have verified everything is connected, everything is put back together then it's time to test!
Plug your surge protector into another surge protector (to avoid burning out anything if a wire did cross). Plug in your sensor/protector into that and plug in a light to your new sensor. Make sure the light is on, the bulb burns bright, and ready for anything else to go wrong or better yet, go right!
Enjoy your new timed sensor!

Step 4: Why?

I think this is the best of all the prop sensors. The step triggers rely on a person to step in the right spot for it to work.
Most store bought props have another sensor that requires some light and a shadow passing by is what triggers the prop from there.
There are plenty of "How To's" on turning a laser pointer into a trigger, but this requires some knowledge of circuitry, and while it is Circuitry 101, its still a bit intimidating for some people. Plus the laser has to be set up for the "target" to walk through it. And of course most of these systems rely on batteries.
This motion sensor is a direct plug in for constant power, has infrared (no light required), and depending on which one you buy, has up to a 270° field of view. That could be narrowed by blocking part of the glass covering the sensor.
Hope this helps for anyone and everyone looking to putting their props on timers, or even lighting a backyard shed! Thank you!