DIY wooden word clock

I once saw this post: https://imgur.com/gallery/TNoh2
So i figured i wanna do something similar, allthough mine is much simpler. The general idea is the same you have LEDs ~1.5cm behind the letters so you can only read the lighten up words. This was a christmas present for my parents and one of the main reasons for me to study EE instead of physics. The next few pictures are kind of a instructional thingy so you can understand how this works. Im sorry for my bad english im not a native english speaker, which some of you sherlocks may have concluded from the clocks language.

I began by sketching 1:1 how the front should look like.

Before i started spending money on this project i first started to code the clock. I used an Arduino Micro. The code itself is very simple, because it wrote it before my CS lectures at uni, so its just very basic if-else statements. The first lines of the code are just basic definitions of how i wanna use the arduinos 20 output pins and i also definied some variables, which i later used for the calculations of the time. At this point you can also enter the starting values, because the clock isnt 24/7 powered.

This is my first idea of how the calculation should work. Even before this idea, i used the delay() command to increase the time but this was simply a bad idea, because it just increases the inaccuracies due to unknown calculation times between each step of the loop (which works like while(1){void main(){...}} in C). So i used the millis() command, which counts the milliseconds since the moment the programme start running. And the rest is just some calculation into smaller values, so it would be easier for me to define the borders for the if-statements later in code.

But there was still one problem left with this calculation. If you compare this picture to the one above you can see, that i changed the if-statement into the modulooperand. The problem with the if-statement was, that it would just once set the time-value to 0, but the next time millis() increases this calcuting wouldnt cause any change in the calculation.

This was the first time i checked my code in reality.

This picture shows the difference between parallel (top) and serial (bottom) connection. Since all letters of one word will always shine at the same time it is efficient to connect them to the same pin. Beacuse there is a 220 Ohms resistor and the pin provides up to 40mA at 5V this would leave the LEDs with ~3V. If you put the LEDs in serial connection the same current runs through all of them but the voltage decreases over the line. If you choose parallel connection they are provided the same voltage but the current splits. But since the intensity of the light is directly proportional to the electromagnetic field energy it carries, which is proportional to the voltage and not the current, since a LEDs uses the reverse photoelectric effect, i chose parallel connections to have all LEDs at the same brightness.

Preparing the wood for the LEDs.

Adding a grid to the front, so the LEDs have a good distance from the letters to create the illusion that the whole letter glows and not only a single spot in the middle of it.

Gluing the LEDs into their spots, hopefully with the right polarity.

Checking the Polarity, because LEDs only allow Current to pass through them in one direction.

This is why i checked the polarity... :/

I started to solder every LEDs, which represent the Letters in the same word, together. Using different colours for the cables to indicate GND or (in this case!) - and pin or + side of the LEDs. I also added the resistors at the end of each units GND-line. I first thought about adding one big resistor at the end of all GND-lines, but in this case the overall brightness would depend on the amount of units, which are powered at the same time, which isnt constant. So this was just one short and pretty shitty idea.

I labeled all the units so i would know which pin i should connect em to. And also built in one big GND-line (the long red cable on the bottom).

Close-up of the switch I added to the GND-line, so its possible to let the arduino run and keeping track of the time without wasting energy on the LEDs.

I added a breadboard and lustre terminals for better fixation of the wires.

View beneath the breadboard.

Mounting walls.

Adding this weird construction, because otherwise the whole weight of the breadbord would constantly pull down the cables and eventually break em.

I always imagined building the front layer would be the most difficult and time consuming part of this project but it turned out to be the easiest. In my small suburby hometown was a small shop which offered to do things like 3D-printing or this stuff. All i had to do was draw what i needed on the computer so in used Inkscape for this. Its free and very easy to understand, so if you need to digitally draw something id recommend this program. Not sponsored ;)

The store i mentioned above used a thin laser to burn the edges of the letters. But this layer was so thick that they needed to burn in the letters three times. Of course they covered it with something that looked like baking paper, but still the wood was slitely burned. So I followed 2 steps for every letters on the clock to remove the burning stains, as illustrated above with the letter "h". First I simply took an eraser and removed as much as i could, then i used the tips of grinding machine and put em on a screwdriver, because it had a higher rotation frequency and very cautiously removed the burning stains without removing the wood itself.

Heres the result after cleaning up the whole frontlayer. This took a shitload of time, since I had to clean every single letter with two different tools.

In order to have a more diffuse effect of each letter i fixed a thin frosted glass film, which is usually used for bathroom doors, with doublesided tape on top of the grid.

Then i added sidewalls to give the clock a better look.

The lever was very hard to pull, so it needed to be glued to other parts very strong, so you wouldnt accidently rip it out if you want to switch it. So I used a epoxide resin my dad found at work. This glue is so strong, its adhesive forces on a circle with a diameter of 15cm can carry a whole car. But it smelled disgusting for like a day in the room I used it in and I accidently spilled a bit of it so i needed to clean it with pure ethanol, which didnt really smell better.

Again adding doublesided tape to mount the front layer.

Putting some felt gliders on the back of the clock so it wouldnt damage the wall.

I also added tiny screws in the corners, because i didnt really trust the double sided, cause it only provided tangential forces against the gravity.

Heres the final result. Id guess that i (with my dads help) have spent 150+ hours of work on this all over 2019.
Edit: Holy shit guys thanks for all the upvotes and positive feedback in the comments.
Edit 2: if the time changes other words shine and it can only show "full 5 minutes" like its ten past 3 next step is its quarter past three.