Introduction: Key Holder


The project you're about to read about was made in a school environment as an assignment. Excuses for unprofessional language/knowledge as my knowledge on 3D printing and electrical engineering is small.

The assignment we were given was to make a prototype using 3D printing machines as a 3D printer, laser cutter and a vacuum machine. We had to include one electrical circuit and a moving joint.

I decided to make a holder for my key. Just like the things you have for allen keys. (see picture)
I decided to fit it with a led light to shine on the keyholes.

Step 1: Making a 3D Model in Rhinosceros

At first i started thinking what shape to make my key holder. And what functionalities it should have.
I decided to make it hold around 3 keys (because this is how much keys i daily use) and i made the choice to have it include a led light to light up your keyholes or just for general usage.

After having messed around with the 3d software i came up with a simple prototype. I used this 3D model to test my 3D printer skills and to acquire some knowledge that could be useful later on.

After printing this first model I decided to give it another shape and to print it differently. Because the inside of the key holder was stuffed with 3D printer stuff to make sure the design was stable enough to print. I therefor decided to print my next 3D model with the open side on top. My first 3D printing session went as planned. But my second 3D model couldn't be printed correctly. The heath plate that was used to print on top off wasn't warm enough. Which caused my model to cool down too quick which made it expand in places it wasn't meant to. What made my 3D model break.

Afterwards I decided to use magnets to keep the keys in its place, it may be smart to include this in the model to make better use of the space.

Step 2: Making the LED Light

In the beginning of this project i decided to fit my key holder with a LED light.
I wanted the circuit to be as small as possible. It had to include a button that would make the LED go on when pressed on. And when releases the LED should automatically switch off.

To make this circuit i used the following thing:
-Blank PCB plate
- White LED
- 3v Button battery
- Button battery holder
- Small pushbutton
- Resistor compatible with your LED

- Soldering iron
- Solder
- Iron saw

At first i drew how i was going to place all the parts on the PCB plate. I tried to place everything as close as possible to each other. I then used my soldering iron to connect them to the PCB plate. Then i used the solder to make connections between the compartments. I then proceeded to cut off the PCB plate around my circuit using an iron saw. After all this I proceeded to take of the edges using a file.

This process all went easily with me. and shouldn't be difficult to do for anyone else.

Step 3: Making the Light Housing

to house the light I chose to make a wooden case for it. Using the laser cutter. I designed the print using inkscape. It has the same shape as the 3d printed piece, so I it could fit on top. At first I forgot to make a hole for the light to come out of. Which made me make a new design including one.(picture) When finished I printed 3 base plates and one upper plate. I included the file of the design I used so you can cut it yourself!

After using the laser cutter to cut everything I glued the parts together. Using wood glue. After letting it dry for a couple of minutes I put the light in its place using duct tape. When the light was in good position I added some hobby glue to keep it in position even better.

Step 4: Making the Key Mechanic

At first I had the idea to drill a hole into the 3d printed hull. And stick a pin up it to go through the holes in the keys. But I couldn't find an easy way to change the keys with this idea. So I came up with another idea. Using magnets to hold the keys. This does take up more space.

I decided to glue a magnet into the keyholder. The magnets make it very easy to take te key out or spin it around.
I used regular hobby glue for this.

Not all keys are magnetic. The key that I used is, but when your key is not magnetic you may want to use another method to keep your keys in place.

Step 5: Glueing the Parts Together

At last I glued the wooden light casing on top of the 3d printed part. Using normal hobby glue