Step 1: Tools and Shopping List
.093”x11”x14” Lexan (or Plexiglass) sheet
Furniture joint connector nut, ¼”-20 thread
¼” x 3/8 flathead machine screw
four neodymium disc magnets .47” x .11” (12mm x 3mm)
Straight and curved files
Various drill bits, including a ½” spade woodborer
“Liquid Nails” clear silicone adhesive
Two part epoxy resin
Step 2: Cutting the Plexiglass to Shape
The Lexan sheet was too thin, so the first thing I did was cut it in half across the long axis and glue both pieces together, resulting in a sheet 11” x 7” x 0.186” thick. A word on the glue: I used three types of glue in the project, Liquid Nails silicone adhesive, two part epoxy resin, and cyanoacrylate superglue. There’s a lot of prying stress put on the various pieces of the batarang while it is being filed into shape, and the Liquid Nails quits after a while. This doesn’t matter, as I had to pull it apart several times to correct mistakes. When everything was ready to be finally glued, I used cyanoacrylate which is notoriously unforgiving of mistakes. For gluing these two sheets together, the superglue is preferable.
I found an image of the batarang on the internet, and printed it out as a template at the size I wanted. Because I was going to have a hinged batarang, I only used one wing as the template for both halves, which helps with symmetry. It also helps that friendly Instructables user, InfiniTTTy, then drew up my template as a nifty .png file, which you can find at the bottom of this page. I then cut out the three pieces of the ‘rang with a coping saw. If you are going to do the cutting with a bandsaw, make sure you have good dust extraction – unlike sawdust, plexiglass dust can get hot enough to catch fire.
I call the three pieces ‘the fixed wing,’ the ‘pivoting wing,’ and ‘the back piece.’ The fixed wing and the back piece will join together to make the 'back assembly,' the half of the batarang you hold in your hand. This is a right-handed batarang, but you can easily reverse the pieces for a left-handed one. The fixed wing is just the pivoting wing with the circular axis removed, and the back piece is just the center of the batarang with a bit of overlap where the magnets will be placed.
Step 3: Shaping the Wings
The next step, after smoothing off the rough edges with a file to make them prettier and easier to handle, is to make the three pieces true to each other. The easiest way to do this is to make the backing piece as perfect and symmetrical as possible, decide which way up it will face, and base the other two wings off that. Mark the center of the back piece with a dot.
First off, try and align the pivoting wing with the backpiece, and correct the pivoting wing where it needs it, using a file. Once the places where they overlap matched up, mark the pivoting wing with a dot that overlaps the back piece dot. Hold the pivoting wing in place with a small clamp or clothespin and shape the fixed wing until all three pieces fit together neatly.
Step 4: Beveling the Wing Edges
When this is done you can glue the back piece to the fixed wing to form the back assembly, the half of the batarang you hold in your hand (assuming you are right handed). When the glue dries, do a final filing and sanding of the places they overlap to make them completely true.
Step 5: Making the Axle
Now make the axle of the batarang. Tape the two wings together in the final position, and drill a pilot hole though the center. Separate the wings again, and drill a hole in the pivoting wing just large enough to accept the machine screw fairly tightly (15/64” was right for me). Then through the fixed wing assembly drill a hole large enough to accept the furniture joint connector (3/8” was perfect). The connector needs to pivot smoothly but not be loose.
I then countersunk the machine screw hole in the pivoting wing, and, using the large 3/8” bit, recessed the other side of the hole to accept a small portion of the furniture connector. This was because the furniture connector was a little too long and I didn’t want the wing to be loose when folded up. I could also have ground down the connector a bit but this seemed easier, and it worked fine.
Step 6: Placing the Magnets
Step 7: Finishing Up
You can now assemble the batarang. I glued a little plastic widget over the machine screw head to cover it. You can still take the batarang apart by unscrewing the furniture connector from the rear. This is why you want to machine screw to be fairly tightly in place.
When this is done, you are almost finished! All it needs is any final shaping and filing, a bit of sanding of the edges, and you are ready to paint. I used a satin black spray paint specifically for plastic, and bronze model paint for the wing bevels.