I've had to do a lot of my homework at night recently due to my work shifts ending very late, and since it's difficult to see the calculator keys in the dark I've been looking at ways to make them more visible. The closest solution I've seen to this is a post awhile back asking if anyone's been able to backlight the keys, but I haven't seen any updates so I thought I might just try something simplier like painting glow-in-the-dark keys.

Anyway, this is a very long way of saying that somewhere along this process I decided that I want to try to make completely new keys so that it's easier to paint them.


First, I took apart my old calculator (the blue one) because it has water damage and hasn't worked in a year, as practice to make sure that I actually could take a calculator apart so that I wouldn't physically break my current one (which I took apart earlier today, I'm currently waiting on my test keys to finish printing, so when they're done I can make sure they fit, and also that the text is legible).


Here's all the measurements I jotted down for the 6 different types of keys on the 84 plus CE, including the bottom cavities on all of them with the little spike-thingys (not sure what to call them).


These are the sketches I made in Shapr3D following the measurements.


Sketched out the text, then engraved them on the models.


This is what all the keys look like underneath.

Currently, I'm waiting on my test prints to finish. I have a resin 3D printer that I've been able to make detailed miniatures with, so I'm hoping the small text won't be an issue. I'm not sure how well these would print on a filament printer, but if anyone would like to try let me know and I can add the stl files here later.

If the prints turn out well, then I plan to get some acrylic glow-in-the-dark paint and dilute it for my airbrush. Since the text is engraved, I'm hoping that I can paint the actual body of each of the keys without the paint getting on the letters.

I'll update with progress photos asap!

(Also, apologies if this is a project that has already been done, like I said before I haven't seen any posts regarding solutions to making the calculator keys more visible, but let me know if there are or if there's another corner of the internet that I haven't seen with information like this and I'll definitely check it out!)

(edit: Sorry that the photos weren't showing, I wasn't adding the link properly but it should work now!)

This looks great so far!

I did backlight the keys with LEDs a while ago in this topic: https://www.cemetech.net/forum/viewtopic.php?p=296907#296907
However, it was such a tedious process I even mentioned in the post:


I'm super interested to see how this turns out. Could you please share the 3D files? I'd love to do this to my other calculators!

I was wondering if anyone had been able to use LEDs as backlights, so thanks for sharing your post! Even though you said it took you quite awhile, the result is very impressive! I might do it someday in the future, I'll have to get more practice in modifying calculators though, I'm still very new to all of this. Which is why I wanted to try just 3D printing some new keys and using glow-in-the-dark paint instead, it seems like a much less intimidating task 😅

Anyway, here are the files: https://github.com/beetletrees/ti84-keys
I added the stl with all the engraved keys, but I also added a file with just the 7 different key shapes in case you want to customize them yourself.

I'm going to be busy for the next couple of weeks, so I won't be able to post an update soon, but my plan is that I'll be able to finishing printing all the keys by tomorrow so that they'll be ready to paint when I get back. I just ordered a couple supplies that will be delivered while I'm gone, so I'll have everything that I need.

From my own experience, most glow-in-the-dark paints don't last very long because it's manufactured with the idea that customers shouldn't have to make the paint glow and that it should already have that quality since that's how it's advertised. A lot of people don't want to or don't realize you have to charge the substance so that it can actually glow.

Basically, to get a material that will actually function well so that I can see the letters and numbers on the calculator keys in the dark, I've decided to just make my own. I ordered some strontium aluminate glow-in-the-dark powder, which (with a UV light at least) you only need to charge for a few minutes to get around 12 hours of a really bright glow, which is more than enough time I need for a late-night homework session. I won't be mixing the powder with my acrylic paint, according to google most water-based substances break down the chemical bonds that allow the powder to be activated so that it can actually glow, and will make the end result not very visible. I still have a good amount of clear epoxy resin from a few years ago when I used it in my crafts a lot, and apparently is perfect for the powder.

I haven't ever made my own glow-in-the-dark substance, so I'm hoping it will turn out well. I hope to post updates by the end of this month though!

*bump* Have you had any success with the glow in the dark powder?

This looks really cool! I'm going to try printing out some of my own on my filament printer and see how it goes.

oh that's cool.
I actually mounted a mirror on top of my calculator so it reflects this light from the screen maybe this would be less crummy.

Sorry that I've been gone for awhile. A lot of life stuff happened, but really I was just busy finishing up my semester, and haven't had any time to actually work on this. Thankfully, I finished my last final yesterday, and I have a few more weeks until my classes start for the summer semester, so I plan on finishing getting this project done!

I printed out the first test set of keys yesterday, and they all seemed good. Everything fit perfectly and there wasn't any resistance when pressing down on the keys.




It's still a work in progress, I've made quite a few changes to the stl files of the calculator keys, nothing major though. It's mainly just small tweaks, and also I wanted them to look as close to the actual keys as possible.

Here's what I worked on today:


I wanted to paint all the keys and calculator shell before adding any glow-in-the-dark to the text. I also wanted to paint the shell a space/galaxy theme since I'm using glow in the dark, before I put everything back together.

As you can see, since I've painted the shell, the 2nd and Alpha outcomes for each button can't be seen, so I've started designing mini 3D models that will act as a sort-of "stencil" for each 2nd and Alpha options.

My plan right now is to finish painting everything, print out the text stencils mentioned above, and then I can start making the glow-in-the-dark component. I think I mentioned earlier that I have some old resin epoxy, and I'll be using that as the medium then add the glow powder to it. Since the letters are so tiny, I also got some hypodermic needles to use to inject the resin into the text.

I actually got 3 different kinds of glow powder: white, blue, and green. I'll be using the white powder for all the engraved text, and the blue and green for the respective 2nd and Alpha options.

I really just wanted the powder to glow enough in the dark so that the text is legible, but when I charged the powder with a UV flashlight for only a few seconds just to see how well it would glow in the dark, I turned the lights back on and it still glowed pretty bright.


Again, this is just after charging it for a few seconds. The glow only lasted for maybe 10 minutes, but the usual charging time is supposed to be a couple minutes and then it's supposed to be able to glow for almost 24 hours.

I've even been looking at used calculators on eBay that I'm thinking about buying just to customize those as well, after I finish the one I'm working on right now. I kind of want to customize another one, since it wouldn't take as long because I already have all the 3D models made.

Anyway, that's all I have for now. I just wanted to post an update with how it's going. I'm super excited to finish this project!

(Also, I'll be sure to update the linked files to the 3D models of the calculator keys when I get the chance, since I've made some changes that are definitely an improvement compared to the original models)

That's looking really good! Cosmetic modifications to calculators isn't something we see a lot of here, though I imagine it's a fairly accessible activity that more people might do if they though about it.

(I'm thinking of a 84+SE I got secondhand that somebody had drawn all over in sharpie (some of it over masking tape); your work is much less sticky!)

That is a really really clean print! A few days ago I tried printing the original files you posted on an old ender 3 and it didn't do so good. Resin printing is clearly the way to go. We'll done! I'm looking forward to those updated files!

I actually wanted to see how the prints would turn out through a filament printer as well, haha. My dad bought himself a Bambu Lab P1P last year and the detail is almost as good as any resin printer! I think the models I made are a bit too small, though, as the prints weren't even able to stick to the build plate 😅

Thanks Tari! I agree, I don't think I've seen many calculators that have been customized or painted. I understand that it's not a priority, though. Plus, I feel like there's a much larger range of things you can do with just TI basic compared to just...painting lol.

I've taken a lot more fine arts classes than mathematics or anything STEM related, but now I'm just getting into coding and I'm sad I didn't start earlier. It can definitely be difficult to learn, but (for me, at least) I feel like I've learned a bunch of new things in just a month compared to the years I've spent figuring out how to draw.