Make Your Own Cardboard Three-Blader
This is an indoor boomerang (but ask permission first)
You will need:
an unused cardboard
large piece of paper
CUT the edges off the top and bottom of an unused cardboard pizza box. (Ask a pizzeria. Note: Corrugated cardboard will not work.) The cardboard must be flat. If it isn't, put it on a flat surface and weight it with books.
Make a pattern: Set your compass at 5 inches and draw a 10-inch circle on a large piece of paper. Using a ruler, draw a line from the edge of the circle through its center, dividing the circle in two.
Leave your compass set at 5 inches. Put the point of the compass where the line you just drew crosses the circle's circumference. Scribe two points on the circumference, one on either side of the bisecting line.
Using a ruler, draw a line from each of the two scribed points through the center of the circle to the other side. Now you've divided the circle into six equal parts.
Set your compass at 1 inch. On every other line, make a two-inch circle, as shown in the diagram below.
On the other three lines, measure 4-1/8 inches out from the center of the big circle. Mark these points. Set your compass at 3-1/16 inch. Using the marks you just made as center points, swing arcs that connect pairs of two-inch circles.
Cut out the pattern.
Now find the grain of the pizza-box cardboard: Hold one sheet of cardboard by its opposite edges and flex it gently. Now rotate it 90 degrees and flex it again. When it flexes with the least resistance, the edges you're holding are parallel to the grain. Trace your pattern on the cardboard so that one wing is aligned with the grain of the cardboard. You should be able to make several boomerangs from each sheet.
Lay the boomerangs on a table to test for flatness. Gently smooth each one with twists until it lies flat.
Gently bend the wings up so the tips are 1/8 to 1/4 inch off the tabletop while the center is still flat. (This flexed position is important: It gives the boomerang stability in flight.)
To adjust for right-handed throwing: With a wing facing toward you, twist it up slightly on the right-hand side. Repeat with the other wings. (Left-handers should bend up the left-hand side.) Very little twisting is needed.
How to throw it
Pinch one of the wings between your thumb and index finger. (Hold it so the bent wings are bending toward you.) You will be throwing it sidearm, tilted about 45 degrees. Cock the boomerang back in your hand, cock your wrist back, and cock your arm back. Throw the boomerang low, snapping your wrist for extra spin.
With practice, the boomerang will zip out, swoop up to a high point, and circle back to hover in front of you.
- Adapted from 'Boomerang: How to Throw, Catch, and Make It,' by Ben Ruhe and Eric Darnell (Workman Publishing, 1985), used with permission.