This is a very simple build, the boomerang itself is styrene plastic although it can be made from any material with a bit of rigidity. I used power tools but with a bit more effort, hands tools can also do the job.

Sokka's Boomerang Build Video

Supplies

TOOLS:

printer

scissors or craft knife

pencil

bandsaw/scroll-saw (a sharp utility knife can work as well)

rotary tool (or 80 sandpaper)

220 sandpaper

#0000 steel wool

SAFETY GEAR:

protective eyewear

respirator

hearing protection

MATERIALS:

sheet of styrene plastic ( or scrap big enough to trace the template)

https://www.amazon.com/White-Polystyrene-Plastic-S...

Rustoleum automotive filler primer

https://www.amazon.com/Rust-Oleum-249279-Automotiv...

black Createx airbrush paint

https://www.amazon.com/Createx-5211-02-Opaque-Airb...

mirror chrome Spaz Stix airbrush paint

https://www.amazon.com/Ultimate-Mirror-Chrome-Airb...

blue 7-31 Badge airbrush paint

https://www.amazon.com/Badger-Air-Brush-Company-Ai...

aqua gloss Alclad airbrush sealer

https://www.amazon.com/Alclad-II-Aqua-Gloss-4oz/dp...

silver Testors model paint

https://www.amazon.com/Testors-Enamel-Metallic-Sil...

*you can certainly substitute brands and colors, spray paint can also be used but the blue likely won't look metallic

Step 1: Prepping the Template

I've sized it to to print on a standard 8.5" x 11" piece of paper (should be easy on the ink as well). Print and cut out the template. Tape it down to your styrene using painters tape or a tape with low/weak adhesive. After tracing around the entire template, cut off the blade edge and trace where the new cuts are (you may have to redo the tape to make sure new marks line up correctly.

Step 2: Cut to Shape

*If you have access to a bandsaw or scroll saw, I highly recommend using power tools to cut out the boomerang. It will be much faster with cleaner cuts. A tedious alternative is to use a hobby (x-acto) knife to slow score the material making many passes until the blade has cut all the way through. This method isn't too bad for straight cuts but curved cuts not so much. Likewise the sanding can be done without a rotary tool but will take much longer.

First drill two holes where you marked earlier using a 1/2" bit. Next began to cut out the the shape of the boomerang. I recommend cutting the curve first as there will be most of the material to use as a handle during the more delicate cuts.

Once cut out, use your rotary tool with a fine sanding drum to shape the blade sides to a dull edge. Using the fine sanding drum will take a bit longer but it's safer removing less material given how thing the material is.

Finally sand all sides with 220 grit. You may want to leave portions of the blade edge a bit more rough for some battle damage texture.

Safety Gear: protective eyewear, respirator, hearing protection

Step 3: Painting

Safety Gear: goggles, respirator

*Paint will often take on the attributes of the layer below. The right color underneath will make the surface color appear the the color claims to be. I tend to use an airbrush for most of my projects these days as they can be used inside easily verses hoping for ideal weather with spray paint outdoors. An airbrush will also allow for more precision. The thinning of pigments also allows you to achieve more realistic metallic finishes.

You will need to paint outdoors or have proper garage/shop ventilation to apply the automotive primer. This primer serves several purposes; filling/evening out the surface, making all sides a consistent texture, and well as polishing to a shiny finish. You certainly don't have to fill all the dings and dents as this gives it that used look. Allow 30 minutes to dry in in at least 65 degree F weather with little to no humidity. Be sure to completely coat both sides and the edges. Using the #0000 steel wool, sand the entirety to a smooth finish. I suggest put down a cover over your work station as steel wool particulates tend to go everywhere and this will make for easier clean up. Be sure to brush off all sanding debris after polishing is finished.

Once, again lay down a cover over your work station to catch overspray. Hit the boomerang with gloss black. Airbrush paint dries fairly fast but can be sped up with a heat gun or hair dryer, these are optional but help if you are in a hurry. I've found that the paint looks more glossy drying naturally. Also the heat can cause air bubbles below the paint or even make the plastic flexible for time so be cautious when using this method.

Next apply the chrome paint, it shouldn't take long for the boomerang to appear metallic. A more raw metal effect can be done with a thinner layer. Finally add the final layer of blue. For my method, paint all sides blue. Sokka's boomerang in the cartoon appears to have a bare metal blade edge by design. I decided to make mine look more used as if it were initially blue but worn over time.

Before adding battle damage. Apply several layers of aqua gloss sealer. This will protect and seal in the colors beneath. Finally, pour out a dollop of silver Testors model paint and use the dry brush technique. This involves brushing off most of the paint before applying. Paint a fairly solid layer of silver on the beveled edge. Lastly, push the brush and a scratch motion start behind the blade edge. Keep direction in mind as you paint as this is meant to look like the paint is being continually worn off. Add a few scratches to the body and back edge for a bit more realism. The testors paint dries very robust and in my experience doesn't need a sealer. Congratulations, you are now finished!