This list of items is what I used to build a pretty simple parking assist for my garage. The Reflective Beam Sensor has a built-in relay that can easily hook up to the Red/Green LED Signal Tower Lamp. The sensor comes with a big reflector, but I opted to use Retroreflective Tape for the garage floor so there is nothing to trip over. Plus if the tape gets damaged, it can be cheaply replaced. The sensor is attached to the ceiling pointed down at the tape. All the wires are ran through the attic. I also didn't want the parking assist lights on all the time, so I power everything via a 24V Power Supply that plugs into a light bulb socket adapter on my garage door opener. When the garage is opened or closed, the lights come on which in turn powers the parking assist sensors and signals. It looks a bit jury-rigged, but it's all safe. Also, since I'm a nerd, I decided to build a "hub" for everything to plug into in the attic. This was built from a small black project box, 1 female DC power plug and 4 CAT5 Ethernet plugs.

PARTS LIST

Seco-Larm Enforcer Reflective Beam Sensor (was on sale for $25) http://www.amazon.com/Seco-Larm-Enforcer-Reflective-Reflector-E-931-S45RRQ/dp/B008G6NLGK/ref=sr_1_1?ie=UTF8&qid=1424747151&sr=8-1&keywords=Seco-Larm+Enforcer+Reflective

Reflexite REF-DB Retroreflective Tape (for garage floor) http://www.amazon.com/gp/product/B0041PBYM8/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

24V DC Industrial Red Green LED Signal Tower Lamp Warning Stack Light http://www.amazon.com/gp/product/B008FZAVW4/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

AC to DC 24V 2A Power Supply http://www.amazon.com/LEDwholesalers-Power-Supply-Under-Counter/dp/B002LMQ6G2/ref=cm_wl_huc_item

Light Bulb Extender http://www.amazon.com/gp/product/B00H8RZPXA/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1

Light Bulb Outlet Adapter http://www.amazon.com/gp/product/B00002NAQ4/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1