The string length is determined by the location of the eye in relation to the door being closed (longest length). A knot is tied (at a measured spot) to stop the ball at the correct height of the windshield-and the slack hangs loosely.
Its a cool, easy, quick and cheap project.
Step 1: Tools and Materials
-Ladder (or stool)
-3/32" bit (used to drill pilot for Eye)
-3/16" bit (used to drill hole in tennis ball)
-Needle nose pliers
-20 feet of paracord (length depends on your garage)
-Fishing sinkers (or similar weight such as screws/sand/etc.)
-Hook and Eye (only Eye used-inside diameter of 1/4 inch)
An automatic garage door opener is obviously needed for this~
Step 2: Prep
Drill a 3/16" hole into the tennis ball.
Insert about 2 ounces of fishing sinkers/old screws/sand/ anything that will fit inside the hole (helps lower the tennis ball).
Tie a figure eight knot at the end of the paracord and shove into the tennis ball.
Step 3: Eye Location
Grab the marker and tennis ball/cord combo
Using the ladder/stool, find the ideal location for the parking aid. I centered the ball on the steering wheel for the X axis, and centered up and down on the windshield for the Y axis. This way- I center the aim the ball center line with my steering wheel.
Mark the location on the ceiling/joist-this is where the eye will be installed.
*Optional-move the car out if you don't want wood shavings dropped on your car-or a cordless drill going through the windshield*
Drill a 3/32" hole in the marked location and install the eye.