The Ultimate CR2032 Battery Holder!

Apologies for the (mostly) joke title. I’m sure this is not the “Ultimate” CR2032 Battery Holder (as there are many) but I do think it’s a good one. Read on for my defense of this statement…

I came into the office one day and Josh said “Hey, I found this CR2032 and printed it, what do you think?” Which was… interesting, because I had been working on a design for a CR2032 battery holder. I didn’t finish it, for whatever reason (I probably started designing something else.) Anyway, I looked at the print and thought… I can do better!

Above is the one Josh printed (in front) and the one I designed (in the back). The one he printed had the batteries a bit too close together, so you couldn’t grab one to get it out using your fingers. For my version, I spaced the batteries a bit so you could grab one. (Note the batteries sort of “snap” in place, they aren’t just held in by gravity.)

My design was still not great… but after about a dozen revisions I had something good.

The design is parametric, and with the OpenSCAD file you can choose how many batteries you want to hold, and (slightly) adjust the space between them.

But the real beauty of this design is that you don’t have to space the batteries enough to grab one with your fingers… With this version you pop them out from the bottom! The batteries snap into place to hold securely, and you press them to get them out. (Check out the video below.)

There’s one more bonus feature… If you print two the same size you can use one as a cover.

Add a rubber band (or a piece of tape) and you’ve got a secure battery holder you could toss into a bag with little worry of any batteries shorting out. Neat!

But wait! There’s more to this story… At some point I asked Josh about the file he found, and he pointed me to the Thingiverse page, at which point I said, “Oh, I know the guy who designed this.” and he said “Of course you do.” to which I replied “Yeah, I hired him years ago for some exhibit work, and I’ve worked with his wife to produce Maker Faire Orlando.” and yeah, sometimes the Maker World seems a little small. But wait… also, I grabbed the files Adam posted and realized he did post a parametric OpenSCAD file! It still didn’t have the pop-out feature I added, but it did allow for changing the spacing of the batteries. (Josh just printed the STL example file that was there.)

So to wrap up, you can see the guide on these at, grab the files from Printables or from GitHub, and do whatever you want with them! We now use these at all the events we do when we have supplies out on the table, and they’ve been a huge improvement to just spill out batteries on the table or keeping them in the (difficult to open) packaging.


Hex Driver Handle

I’ve seen a few handles that convert a hex key into a “screwdriver” style tool, so I figured I would make one. (I’m sure there are better ones, but this one is mine!)

This one is two pieces. The main handle has a slot so you can insert the hex key, and then a piece to put into the slot. (Which I call the “Slot Filler” of course.)

When I printed this on the Prusa (not pictured) it came out perfect, and the slot filler filled the slot… perfectly.

When I printed it on the Maker Select Plus (the red version in the photos) it… well, fits, mostly… sort of. Hmmm. I had to X-ACTO knife away the blobs on the end. (Sorry, but the Prusa just prints better!)

You could always glue the slot filler into place I guess. It’s a wedge so it should “wedge” in place. In theory…

The first version had no slot filler, and no hole for the short end. I just smashed it into the slot. I figured making it removable might be a better option though…

Maybe it’s not a god idea? I don’t know. I did widened the slot a bit and added the slot filler. I just like designing these things and testing them out.

You can get the STL and .scad file from – Hex Driver Handle (2mm). Print it if you need it!


Wire Spool Holder

I use these spools of silicone wire and they come in a cardboard box with a hole to feel the wire through and every damn time the wire goes back into the box and I have to open the box and feed it through again and wow it’s a pain! This is an attempt to solve that…

Like some of my other designs I wanted a modular thing. The wire comes in six spools/colors but rather than one huge print each spool has its own holder. This makes sense to me. I thought about ways to interlock them, but eventually decided to just add screw holes and mount them all to a piece of scrap 1/4″ plywood that was near the laser cutter.

The hole the wire feeds through is just right for this wire. YWMV (Your Wire May Vary!) The OpenSCAD file allows for adjusting the hole. An X-ACTO knife or drill bit could also be used to fine tune things.

Advantages of this design? It is stackable. I can put stuff on top of it. (Maybe more wire spools?) I can pick up the whole thing easily. There is not one rod holding all spools, and you can easily remove/replace a single spool.

So far I’m liking this thing. It’s similar to my Chonky Solder Spool Holder. It took about four revision to this before I had the final version.

Here’s the first attempt. It was too difficult to feed the wire through the hole, so the hole got moved up and the half-circle notch was added to allow getting a finger in there to feed the wire through. The bottom lip was also added to allow for mounting to the board with screws.

You can get the STL and .scad file from – Wire Spool Holder. Print ’em if you need ’em!


Headphone Hanger (in OpenSCAD)

I wanted a simple headphone hanger for my office at work and I found a few really nice ones on but I wanted one I could easily change the mounting holes on, so I whipped this one up in OpenSCAD.

Does it sort of look like a dollhouse bed? Yes, it does…

Can of some weird seltzer my wife drinks for scale… Also, I made it parametric so you can make it longer or shorter if needed.

Here’s a really long one…

And here’s a really short one…

And here’s one that’s juuuuuust right!

If you change the length remember to take into account the full depth of your headphones, not just the band that goes on your head, otherwise they’ll hang at an angle against the wall. That long one could probably hold all of my headphones! (I have four pairs. All of the other ones are Sennheiser but the ones I have at work are some Audio-Technica I got from the dumpster.)

You can get the STL and .scad file from – Headphone Hanger. Print it if you need it!


The (Prusa) Blob

It’s been just over a year since I got the Prusa MINI+ 3D Printer and besides a few minor hiccups at the start it’s been a great experience. I’ve printed hundreds of things without issue in the last 13 months. Sure, there have been a few failures, but they’ve been pretty minor… until now.

A few weeks ago I had some issues printing because I’m in Wisconsin and it’s winter and it gets cold in the basement. If the printer sees a low temperature it assumes something is wrong with the thermistor and won’t print. It’s a safety feature, and probably a good one (though I would like a way to override it.) My “manual override” involved running a small space heater in the tiny room the printer is in. It works, and It’s usually not so cold I need to do it often.

Now, I know a lot of people who get a printer post online immediately “What upgrades should I do first?” and that makes sense if you get a cheap printer where costs were cut. But hey, this is a Prusa! It should be good out of the box. In fact the only modification I did was to add a silicone sock around the heating block to prevent a big blob of filament sticking in the event of a failed print.

So when it was really cold, and the printer wouldn’t print, and I was using the space heater… guess what got the printer printing reliably in the cold. Removing the silicone sock.

No sock, no problem, right? I started a long print and went to work. During the day I checked the camera that points at the printer and noticed the plate had moved. Argh. It’s happened before, so it’s usually just a failed print.

I checked again later and the plate was gone… It was probably thrown free from the printer. No a disaster, but annoying for sure. But wait… can you see it?

I found the plate on the floor and a bunch of useless plastic. Oh, and… The Blob!

Dammit! I heated up the printer and got the large blob loose, but it was all over the place. I grabbed the heat gun from my soldering station and (somewhat carefully?) heated and removed as much plastic as I could. Did I slightly deform the printed fan duct? Yes. Is there still plastic on there. Indeed. Did I put the silicone sock back on, but have to cut it to get it over some of the stuck on plastic. Ugh. Yup.

I haven’t done a full tear-down or clean-up but it’s printing again, and prints look fine. At some point I should probably get it cleaned better… or, you know… buy another printer. ;)