Throw some extra badassery into your outfit! These hollow, durable carbon fiber spikes look great, and yet they shouldn't hurt anyone who unwittingly bumps into you.

As for yourself, your worries are over! Anything you might bump into will be gently spiked before it gets close enough to hurt.

The perfect project for introverts... Turn yourself into a hedgehog. A porcupine. A virus. Vegeta. The spiky opportunities are endless!

Just don't be too attached to uniformity, especially if you're using carbon fiber for the first time. This is all hand-shaped, so it's imprecise by design. I'm using them as part of an animatronic mohawk.

Materials

Wood scraps
Vacuum former and suitable plastic
Carbon fiber cloth
Epoxy resin
Dremel, with cutting wheels and engraver tip
Shop utilities (clamps, fan, etc.)

Step 1: Carve It Up

Go to your local woodshop and find some wood scraps. Then, using whatever method you prefer, shape them into spikes – a bit smaller than how you'd like the end product to appear. (The layers on top will add 1-2mm of thickness.)

I chose a piece of 3/4" thick wood, and used a bandsaw to cut it into elongated diamonds.

Then, I used the disc-and-belt combo sander to shape each piece into a nice claw form: one longer, one shorter, one right in the middle.

I left the bottom flat, because these pieces will be sitting on a vacuum table in the next step. The bottom will be open in your end product.

Also, since you're going to be vacuum-forming these, try not to undercut: that is, try to make them completely convex in one direction. This prevents the wood piece from getting stuck in the plastic, and you'll get fewer unsightly issues.

Finally, try to make the slopes gentle wherever possible. Sharp angles are just a little more tricky to vacuum-form. Your edges will end up nice and pointy anyway.

Step 2: Go Astray

I did a little test first, trying to make these out of thin sheet metal that comes in a roll from the hardware store. The pictures above essentially demonstrate the process:

Trace the shape you want onto a piece of paper laid over the wooden form;
Cut out the shape and tape it onto a piece cut out of the metal, then cut that out;
Stick the metal to your wooden form and smoosh the metal onto the wood, using your fingers and/or a light hammer. Trim up the edges a bit more, if desired.

You don't even have to trace the paper onto the metal before cutting it out, but if you do, make sure you do it on the side that'll be invisible (obviously).

You may actually be able to cut the thin metal with scissors.

The resulting metal claw-thingy was too flimsy for my needs. It would have been crushed the first time I tried to transport it anywhere. INSUFFICIENT!

Step 3: Suck It In

Now that you've given up on that fool's errand, arrange your nice new wooden spikes on the vacuum forming table (along with some other small bits and bobs, if you don't want to waste space).

Set them widely enough apart that you won't get "bridges" between them: Picture stretching a piece of fabric over two chairs. If you put the chairs far enough apart, the fabric can touch the floor between them. But if they're close together, the fabric has no room to drape. Although the vacuum table is specifically designed to prevent this problem, creases can form if there isn't enough space.

Since most wood is fairly porous, you shouldn't need to drill holes in the pieces. Still, try to set them in between the holes in the table, as much as possible. You want holes close to the edges, so that you get suction right next to the face of the object, but not underneath.

Then, flex your vacuum-forming skills! Turn on the heat and let the plastic sheet sit up under the heater until it sags down enough to properly seal in your objects. Then, lower the plastic and turn on your vacuum power! This sucks the plastic down onto the table, around your forms.

Step 4: Pop It Out

Pop out your wooden forms from the cooled, hardened plastic sheet. (You should be able to keep your hand on the plastic for 5+ seconds before turning off the vacuum power. Don't be a hero, either.)

You'll need some "hem" around the edges, to hold onto.

Step 5: CARBON FIBER!

Okay, I'm sure someone else has done a much better instructable on this than I could, but I'll touch on the process here.

Get some 2-Ton DevCon epoxy resin. Not the 5-minute stuff! You won't have enough work time, unless you're only doing one spike... which is kind of a waste.

You'll also need your carbon fiber fabric (coarser weaves are cheaper), scissors, GLOVES!, a disposable mixing cup, and stirring/spreading sticks.

Cut pieces of the fabric that cover your plastic forms, with enough to drape. Fortunately, this stuff is quite flexible, as long as you don't mind having little holes in some places where the fibers pull apart.

Mix the two parts of epoxy together, a couple of tablespoons each, in your mixing cup. Spread a thin layer over one plastic base, then smoosh the fabric onto/into it, then (if you need to) go over it again with another light layer of epoxy. This will make the surface nice and shiny!

Leave the forms to cure. Be careful: once the carbon fiber fabric dries, any raggedy spikes will actually become super dangerous. They can spike you really easily, and very painfully. Watch your fingers!

Step 6: Cut It Out

Oh, man. This is the biggest pain.

First off, when you're grinding carbon fiber, you NEED a good face mask to keep the toxic, itchy dust out of your lungs. Make sure you're also wearing goggles (!!!!), as well as gloves and some kind of arm/body covering. That dust gets everywhere, and IMO, it's worse than fiberglass.

Clamp the fibered-up forms to the edge of a trash can, in a very well-ventilated area. (No sense giving everybody else cancer as well.)

Now, go to town with your Dremel or other rotary/grinding tool. Tin snips don't work on the hardened epoxy and fiber.

Figure out whether it's easier for you to cut, and to stay on target, if you work from the inside (plastic side) or outside (fiber side).

Try to be consistent with how you cut them. Inside the edge? Outside the edge? How short do you want to make them?

This part can be really frustrating, as you'll probably break a fair number of cutting wheels. Keep at it, tiger!

Step 7: Done!

Now you have a spiffy set of spooky, shiny spikes. Use them for good!

You can use a Dremel with an engraver tip to make holes in these. I needed small holes, so I used the big Dremel tip I had for chomping through the plastic and resin. The fiber resists more, and at that point I broke out a small, batter-powered hand engraver to do the final honors with more precision. It worked a treat.

Once again, wear a mask, be safe, and have fun. :)