If you want a small and shiny finalkey like this you have to move some components from arduino micro pro or you have to move light from one place to another. Lets see how this is done for the Alien Artefact.

Alien Artefact : a shiny finalkey with a small form factor

alien artefact finalkey

Parts used

parts used for finalkey : alien artefact
  1. arduino micro pro
  2. brass rod, 1mm thick, about 12 cm long
  3. 24LC512 EEPROM
  4. 2 x 4,7 kOhm
  5. 2 x acrylic poles, 3 to 5 mm diameter and 5 mm length ( to send light from green and yellow led to surface)
  6. 4 cm optic-fiber/fiber glass (to bend light from red power led to finalkey surface). Remove the cover only after gluing one end, otherwiese you will have a problem finding all fibres once they are loose.
  7. red smd led (finalkey led)
  8. 160 (up to 470 Ohm) smd resistor (to set current through finalkey led)
  9. One red or one transparent gemstone, flat (1-2 mm thick), 6 to 10 mm diameter ( to cover red finalkey led and make it even more shiny)
  10. small pushbutton (reset) , optional see 10.
  11. large pushbutton (finalkey button)
  12. 1 stripline of a perfboard (to set up red finalkey led)
  13. 2 component glue, curing fast/5 Minutes (to hold small stuff in place)
  14. 2 component glue, curing a long time/24 hours but very stable (to attach the brassrod to arduino)
  15. repair glue, 2 component ( to build the body/cover of the alien artefact)
  16. some drops of blue tint/tinting paste
  17. black varnish
  18. gold varnish
  19. nail top coat or anything which sticks to the black and gold varnish and protects it without ruining it


Technical Problem: 2 leds at the same place?

I wanted to get a small form factor and a large shiny red finalkey light. As the power led was next to the place where i wanted my finalkey-led i had to move the light from the power led to some other place. There was no space left for any other led. So i decided to just bend the light to a small space between the green and yellow led. This can be done with optical-fibers.


Check functionality after each step is done!
If you discover any serious error after step 11 you have nice brick :(

1.      FinalKey basic setup
1.1    Program arduino with finalkey software -> see dusteds setup.
1.2    Glue and solder eeprom to arduino board.
1.3    Glue and solder big pushbutton to arduino board.
1.4    Solder 2 x 4.7 kOhm.
2.Bend brass rod and glue it around the arduino micro pro board.
3. Glue 2 acrylic poles onto green and yello led of arduino micro board -> image at 5.
4. Prepare finalkey-led with a mini circuit board.
5. Glue fibre optics to red power led of  arduino micro pro .
6. Glue big pushbutton onto eeprom and adapt wirelength.
7. Bend optic-fibres around eeprom and upwards between red and green acrylic pole, glue into position.
8. Glue finalkey stripboard to arduino mini pro.
9. Glue gemstone on red finalkey led.
10. Connect reset button and glue it into place.
11. Cover your creation in repair glue.
12. Sand it, color it, varnish it.

1. FinalKey basic setup

Program your arduino before attaching any components to your board.
A fresh and clean arduino allows for easy access to programming pins. If you glue and solder stuff first then programming pins will be blocked.
If you use arduino IDE and an usb cable from pc to arduino micro pro you will be able to reprogramm your finalkey later by using the reset button. This is what i did with the Alien Artefact. If you do it be aware that this is a potential security risk.

If you write FinalKey software to your arduino by using an ISP programmer and the MISO and MOSI contacts on your board it will kill your bootloader. The Reset button will not get you to programming mode afterwards. You will not be able to reprogramm this finalkey without some serious hard work and with a high risk to brick it. ISP programming is more secure because anybody who finds your key will not be able to read your eeprom without ripping it off the finalkey hardware.

2. Bend brass rod and glue it around the arduino micro pro board :


Brass rod/wire, 1mm thick
Brass rod (1mm) is easy to bend and strong enogh to make a proper handle. Thinner brass rod is too soft. Thicker brass rod is very hard to bend. Aluminium is too soft. Anything with  plain iron will rust. High quality steel is too hard. Silver is too soft. Go for gold alloy, used for tooth crown, if you have the money. Its even shinier than brass ;-)
dremel or sand the edges of arduino pro to get "round" soft edges at the usb side of the board
It is close to impossible to bend the rod to a 90° angle. Its always a bit round at the edge. As you will want a close fit you have to get rid of the sharp edges at the usb port side of the circuit board.
This is not a problem on the other side (not usb ...). There is no 90 degree angle for the brass rod.
cut about 12 cm from a brass rod of 1mm diameter
Do this first because its handy to have an extra part to handle the arduino in all steps following. Dont use anthing thinner, because its too fragile then. Dont use anything thicker as 1 mm as it will be very hard to bend.
bend 3-5 mm as tight and close to 90 degrees for the usb side as possible
If you sanded the edges properly, the rod will have a tight fit which is essitial for handling the board afterwards. These bended parts of the rod take the load for any drag on the opposite side. If you dont have tthem the glue at the sides of the board has to take the load alone. This is not prefereable.
bend it to a curve on the other side with a distance of 1-2 cm from the board
If you need a large curved rod to even put your finger through it, make it larger. I only want it to hang an a hook or to attach it to a key ring.
bend it as tight and close to 90 degrees as possible for the other edge close to usb.
Cut off  the part which does not fit :).
              brass rod bent and ready to be glued
see 2.2
Its no problem if the rod just slightly touches the usb port as it is grounded. But the rod should not move away from the board because the bent part is too long. Remember : a tight fit is the goal.
Bend it a little more than necessary, like in the image to the left. It will clamp itself to the board and is easy to glue.
If its too loose you will have a lot of trouble glueing it.
make sure to have a flat construction that fits exactly around the circuit board
              test how brass rod fits
If your construction is not flat you will not be able to glue it around the circuit board. Instead you will be ruining your fingers, the circuit board, your clothes and anything close to your handling area in the attempt to get it done.
If you get a fit like the one shown in image 2.5 you can lift the board and the rod will still cling to arduino. Now its ready to get glued.
Glue it around the board with heavy duty two component glue and let it cure. Make sure that it does not touch any contacts/conducting parts.
Dont use too much gluu. You might spoil contacts on your arduino board.
If you have a glue which is more fluid than solid then solder stuff first and glue afterwards. If you have some gelatinous glue its perfect.
I always use a strong 24 hour curing 2 component glue to make sure that i get a strong and durable connection. Dont use super glue or any stuff which goes hard like a crystal after curing. Its not very usefull for parts with large gaps. And dont use anything soft like regular paper glue. It will not even hold the circuit board alone if bad luck hits you. Hot glue might be an alternative if you have a gluegun with a very fine tip. Otherwise you will find glue all over the place. And its not as strong as i want the bonding to be.

With the rod attached you now have a good handle for the steps following.

3. Glue two acrylic poles onto green and yellow led of arduino micro board (see image below)

4. Prepare finalkey-led with a mini circuit board

Cut off one line from a stripboard, seven holes long.

one line from stripboard
This line will fit onto the arduino micro pro board.
Any stripboard with 2.54 mm distance between holes will do it. Otherwise you have to recalculate length. Anyway, only one hole has to fit exactly : GND. The other end will be connected by a wire, so there does not have to be an exact match of holes at the ends of our mini-led-board with the arduino board.
Cut the copper line at 2 holes, one exactly in the middle, thats where the led goes.
cuts in led stripboard
The two cuts are the mounting places for a resistor and the led. The resistor has to have a minimum of 160 Ohm.
A red LED needs about 1.8 Volt at 20 mA. As we are running our finalkey from usb port, 5 Volt will kill it without a resistor taking the voltage up to 5 Volt.
R=U/I -> R= 3.2Volt / 0.02 mA -> R=160. Depending on your LED and its brighness you can go up to several hundred Ohm and it will still be bright. Nowadays LEDs might blind you if you run them with maximum allowed current.
Solder resistor and led over cuts, test it at 5 Volts ! Resolder if necessary.
mounted resistor and led on

I used a 180 Ohm resistor which protects the red led and still allows enough current to make it shine bright.
Dont connect it to arduino yet.
NO GLUE, NO SOLDERING to arduino. You have to glue fiber optics to red power led first. This is located to some extent below the finalkey led stripboard.
See image 4.4.
Attention reset button users :
If you want a reset button you better solder the resistor to the right and cut off 2 holes from the stripboard on the left. You will need this space for the reset button

Solder connections for GND and arduino output . DONT connect it to arduino yet!

The connected wire make a good handle, the ground pin makes it easy to adjust the board for the following 2 steps.
Mark position of red power led on your stripboard
                location of power led on finalkey led board
Dilemma dilemma!
The red power led is partly covered by the finalkey stripboard mount.
Solution : mark the position of the power led and remove some stripboard.

You might turn the board and connect ground to the other side of the arduino board. There are two GND connectors. But this option will give you more pain to run fiber-optics below the finalkey stripboard.

Cut a path for fiber-optics at the mark you just made into your stripboard. You should have a clear view to the red power led on the arduino board now (inside red oval)
cut path
              for fiber-optics
As you will glue your fibers at an angle of about 45 degrees you need some space below the stripboard. Once you can see the power led  like this (see image 4.5) you are done with the stripboard preparation.

If you have a shortened stripboard to have some space for the reset button you will not need this extra grinding

5. Glue fibre optics to red power led of  arduino micro pro

arduino micro pro with
        mounted fiber optics
Arduino pro micro with fiber optics (left, ontop the red power LED and glued light pipes (right to eeprom, clear)

Glue one end of your fibers  about 2-3 mm so that you can cut them to an angle of about 45 degrees afterwards.
Let it cure
As the fibers are to be bend around the eeprom it is not a good idea to mount them vertically. They are flexible but if you try too hard they will brake.
Cut the glued fibers at an angle of about 45 degrees on led
(see image above).
Glue it to red power led (see image above)
Dont use too much glue otherwise your finalkey-stripboard will not fit and you have to do more grinding.
To get a good transition of light from led to fibers -> 45° +/- 10°  will do it.
Use a fast curing glue (minutes) otherwise your hand will get tired. A 3d hand or any mechanical solution will most probably not do it.
Cover the glue with black paint or any non transparent color or glue.
If you dont cover it there is enough light left outside the fibres to irritate the finalkey gem above .

6. Glue big pushbutton onto eeprom and adapt wirelength.

     See image below at Nr.7. Button is connected to pin 7 and 9 (two white cables, bottom right)

7. Bend optic fibres around eeprom and upwards between red and green acrylic pole, glue into postion

The following image has more stuff glued already : fiber optics have been marked red.
The upper part on the right will be cut later  to match surface.
The finalkey led is covered already with glue (the more or less white stuff the arrow is pointing to)

finalkey 1 with mounted stuff

8. Glue finalkey led stripboard to arduino mini pro.

Glue it over fibre-optics.
Connect it to GND and arduino pin10.
( the yellow cable seen in the image above is connected to reset! The finalkey-led cable is running to the other side in front of the pushbutton to pin 10 . Its covered with glue in this  image already.)

9. Glue gemstone on red finalkey led.

If you get cheap gemstones from a dollar/euro-shop they will most likely have a reflecting backside. If they do, you have to remove some part of it to let your led shine through. Otherwise you will not see your led blink.

gemstone preparation

1 : gemstone front, not prepared
2 : gemstone backside with part of the reflector removed. This is where your finalkey-led will sit. 

Dont remove all reflective layer. If you do your gemstone will be less shiny.

Try to put your gemstone exactly above the removed part of the reflector.

10. Connect reset button and glue it into place.

The reset button is not necessary for regular use. Only if you want to write your own code or you want to debug your code its useful. And as dusted emphasized : its a security risk. You can only program arduino by usb once its covered. Anybody will be able to read your eeprom by using the rest button to get into programming mode. Its crypted, ok, but its a risk anyway. I have used finalkey several month now and it never got stuck or needed a reset.

11. Cover your creation in repair glue.

12. Sand it, color it, varnish it.


              (thunderchild), logo

Design and hardware extensions used for
Red Heart, Alien Artefact and Green Miracle :
tc (thunderchild), Nov 2014

All praise and credit for FinalKey hardware and software go to dusted.