Save yourself some money. Get a small Maglight flashlight, or a I call it "laglight". Find a straight seem in the carpet or the base board along the floor. Put the flashlight in your right hand(specifically the light should emit from the #3 pressure point, You right index finger) if you are a right handed golfer. Trace with your right index finger along the baseboard or seem (base of your plane line). The light should not leave the straight line on the ground until it gets parallel (horitonzal) to the ground.
When working above horizonal, simply flip the flashlight arround or get another one and tape it end to end with the first one.
As Homer says, " Whenever the clubshaft is parallel to the ground it must also be parallel to the base line of the inclined plane which is usually the line of flight. Otherwise, the end of the club closest to the ground must be pointing at the base line of the inclined plane or extensions of that line, even if they must be extended to the horizon. Remember, a flat plane has a straight baseline. A circle is two demensional and can lie on a flat plane. If the plane line loses it straightness the clubhead orbit becomes three demensional and precision vanishes."
