Weekly Update #5


I finished up routing the traces for the lights in the brim. You can see the circuit in the middle picture. Note the lights don’t go all the way around the brim – see the problems section. I’m gonna forge on ahead as-is, but this might be a spot for improvement in the future.

In the last picture, you can see the chemicals needed for etching the board. The classic chemical is ferric chloride, but that stuff is difficult to dispose of and hard to find. I went with another mix, which is basically just hydrogen peroxide and hydrochloric acid. It’s easy to source with a single trip to Home Depot and I can dispose of it down the bathtub with plenty of water. People use this stuff in their pools – diluting it makes it harmless.

You can also see the splash gear in the third picture. They don’t sell Tyvek suits in my size at Home Depot. The smallest I could find was an XL. Also those things do not breathe at all.


Pattern printed and cut out. Still need to apply it to the fabric. I’ve got some nice light-ish black canvas to use.

Finished the resist for the etching. Also acquired the materials necessary to do so. It’s one part 3% hydrogen peroxide to one part 37% muriatic acid. A little goes a long way with this stuff. Got the safety gear to protect against any errant splashes as well.

Located a laser printer and tricked it into printing on glossy paper. The toner laser printers use is really just melted plastic powder, so it’ll stop the etching process wherever it’s bonded to the copper. The glossy paper means it’s easy enough to transfer to the copper with a clothes iron.


Some of my components seem to have gone…missing? Sparkfun says they were delivered, but I never received the package. I’ll have to follow up during the week. The parts there aren’t a bottleneck for construction, so worst-case I just expedite ship some replacements and continue as planned.

An interesting issue I didn’t foresee – the software I used to route the traces and make the resist puts a hard cap on the size of the boards you can make without paying for a commercial license. Which is like 1.4k, so I’m not doing that. There are alternatives, but their interface is different enough I’d basically be redo-ing all of the work. I’m going to proceed as planned, with a more narrow display, and if I have time maybe go back and adjust.

I’m also living the bachelor life and don’t have an iron, so I can’t apply the resist to the copper. I can just take care of that during the week.


Etch. Monday evening is for testing the mix, Tuesday I’ll apply the resist, and Tuesday night I’ll etch and solder.

I also need to cut the pattern out of the fabric I picked up and sew what I can. without the brim being totally done.