Open the paper, and you now have a line directly in the middle. Make a firm crease along the top of the paper, fold it backwards along the same crease, and split it in half. It's important to be as precise as possible. Fold it in half, hot dog style (the long way).Normal, run-of-the-mill paper is best.Either way, work with something similar to 8.5" x 11" (21.6 x 28 cm). Take it out for a test drive before you break out the paints. Don't decorate the boomerang until you're sure you're all finished.Then, apply a thin coat of spray paint or clear lacquer to help protect the boomerang and make it look nice. Give it a final sanding with fine grit paper.The optional finishing touch to shaping the airfoil is to slightly bevel the back edge of the wing (if you wish). 49 and 50 cabinet rasps are good places to start. There are a variety of rasps available out there. Shape the airfoil with rasps, files and sandpaper.In addition, you want the whole surface to be smooth. The boomerang needs leading and trailing edges, just like an airplane. In the middle of the boomerang, blend the two airfoils together.The best choice is to find a position in which the boomerang wings tips are up. The traditional Australian boomerang has positive dihedral (an angle formed by two plane faces).Note that you only have to shape one face of the plywood. The quarter-round shape generally extends about 1/4″ (6 mm) from the edge, while the trailing edge extends about 1″ (2.5 cm) to 1 1/2″ (3.8 cm) into the material.Mark in on the top the distance that the contour retreats back from the boomerang’s edge to its top surface. A marking gauge can be used for this (or the old trick of holding a finger against the edge). Lay out the leading and trailing edges of the wings based on which hand will do the throwing.The bottom face of the wing is completely flat. Mark the two leading edges and the two trailing edges so you do not file them incorrectly. The leading edge is a quarter-round shape and the trailing edge tapers off the top of the boomerang like the cross-section of a typical airplane wing. As with airplane wings, the airfoils on a boomerang have a leading and a trailing edge.
![airfoil 5.6.3 airfoil 5.6.3](https://i.pinimg.com/736x/0e/a4/03/0ea403277eff229b1d3269976180d7a7.jpg)
![airfoil 5.6.3 airfoil 5.6.3](https://i.imgur.com/Gwxtf72.jpg)
The direction the airfoil faces depends on the hand with which you throw. Use a sanding block (and a lot of elbow grease) or an orbital sander to give each side of the boomerang an airfoil shape. If you make the angle greater than 107 degrees, know that the rotation plate becomes small and it can be difficult to keep the boomerang spinning. If making the standard "V"-shape boomerang, the 107 degree angle size is not critical, just optimum.Use Baltic or Finnish birch something sturdy. You also need some sort of saw that can cut curves, such as a band saw, coping saw or bow-saw. There are many types of boomerang designs to choose from and a good pattern can be found online. Trace your pattern onto plywood and use a saw to cut out the shape.