Straight fins are next to godliness
If you want your rocket to fly straight with no wobbles or twirls, you have to get the fins on straight. Estes Tube Marking Guide is an easy way to mark fin and launch lug placement lines.
It fits all current Estes body tubes (and everybody else's, too). It can quickly marks 3 fin and 4 fin configurations and with a bit of jiggery-pokery, 6 finned birds, too. A fin gluing jig for smallish balsa fins is included, too.