Hat Hacking

So we’ve got a little problem…

We’d like for — no, we need — the pixels to form a fairly uniform grid, so we can draw legible text.

As previously mentioned, the hat is not a perfect cylinder…it’s tapered. If we simply coil the NeoPixel strip around it, the circumference of each loop is slightly different, and everything will be a jumble rather than a neat grid. Even if you do find a straight-sided hat, the circumference is very unlikely to be a precise multiple of the pixel spacing along the strip.

To address this, we’ll build a sleeve that slips over the hat. This will give us straight sides and an ideal circumference.
First order of business was to cut and peel the hat band off; it interfered with the fitting of the sleeve. Doing this may leave hot glue stains behind. Rubbing alcohol and some scraping with an X-Acto knife helped somewhat. But no biggie…most people will be too dazzled by the LEDs to notice.
I’d originally made a sleeve out of a certain type of heavy acetate film, before realizing another problem: my craft stash has stuff dating back to the Byzantine Empire. The well-stocked local art supply shop is an extinct bird, and I don’t want to send anyone on a costly internet goose chase for one simple material. This is where the maker ingenuity ingredient comes in: some possible alternatives are mentioned below, but maybe you have better ideas for cheap materials you can source locally.

Card stock or poster board are reasonable last-ditch substitutes, but something plastic is much preferred. Not expecting anyone to wear this in a downpour…but sometimes one is caught off-guard by a little drizzle or fog, and paper would just go pulpy and fall apart.
Fail: one material I’d experimented with was plastic canvas (aka needlepoint mesh) and small cable ties, which could be found in more mainstream craft and hardware stores.

This almost worked, but the material seemed just a bit too thick, and all those cable ties added a lot of ugly nubblyness.

If you have the patience to do this with actual hand sewing instead of the cable ties, I wouldn’t rule it out as a possibility! Read on regardless, there’s still the matter of sizing and assembly…
To wrap around the hat, we’d like to find a thin, flexible plastic with just enough “body” to stand up on its own when formed into a cylinder, but not too thick and bulky. It should be a minimum of 4.5 inches (115mm) wide, and 2 feet (600mm) long or more (notice above how the needlepoint mesh had to be joined from two smaller pieces — the local craft store stuff is only 13.5 inches long).

Ideally, the material would be affordable and easily found in a local “big box” store. There were field trips involved.
Craft foam? Too thick. Poly envelope? Too flopsy. Vinyl floor runner? Too thick and too flopsy. The placemat looked promising (and on clearance! And BATMAN!)…
…but ultimately arrived at the thin plastic used for 2-liter soda bottles. Can find these anywhere!

Two bottles provided sufficient plastic to fit around the hat and sufficient caffeine to complete the project. Diet soda, though vile, rinses out nicely with no sticky residue.

Coke bottles were unsuitable due to their funny shape; had to be something with straight sides.
The tops and bottoms were cut off the bottles, and the resulting tubes were sliced down one side. These were then unrolled, laid down flat and trimmed more carefully to 4.5" wide.

The two pieces were joined into a longer strip (overlapping about 1 inch) using packing tape on both sides.
The resulting plastic strip has a strong proclivity to roll up. That’s okay, it’ll behave better once wrapped around the hat…
Hold the sleeve in place temporarily with a piece of removable masking tape on the inside. Don’t join this side with packing tape…the circumference is going to need some tweaking.
On the next page, we’ll start coiling the NeoPixel strip around this sleeve.

The silicone coating on the NeoPixel strip is wonderful for weatherproofing, but does present a challenge: almost nothing on this planet sticks to silicone!

Fortunately there’s one thing that sticks just well enoughcarpet tape. Most hardware stores carry this. It’s a double-sided tape that’s wicked sticky and has a removable waxy paper covering.

Cut and apply four strips of carpet tape to the sleeve, running vertically: one each at the front and back, one on either side. Leave the paper backing in place until the next step.
Don’t worry if these aren’t straight, they’ll be covered up. And if you cut a piece too short, just add another small piece to make up the difference.
This guide was first published on May 01, 2014. It was last updated on Sep 19, 2018. This page (Hat Hacking) was last updated on May 04, 2015.