Subtle color-changing Crystals.

Summary

After a make of my previous model Led Light (Crystal on Rock) - USB powered was posted with the use of multi-colored LEDs, I decided to do more with this. 

It kind of ignited my imagination....
The model now presented is the result.

The use of transparent print material for the crystals and a dark base in the shape of a rock with many sloping and undulating surfaces creates a very beautiful result, both in the brilliance of the crystals and the play of light on the rock.

The 2 basic parts themselves are very easy to print and standard color changing LEDs are used for the lighting. All this is powered with a standard USB cable.
The only other thing required is that you can solder a little. Than this is a very easy project.

The (bright) photo's and the video are taken with daylight to show detail of the Crystals.
In the dark they really glow bright!

Printing the 2 parts

The crystals are all hollow on the inside and contain a recess in the bottom in which standard 5mm LEDs can be placed. All crystals are placed at slight tilt angles from each other, but together they form one block which is placed in the rock as a whole as an insert.

Print the Crystal Insert with clear PLA or PETG (I used PETG for this).
I used a 0.4mm nozzle and a layer thickness of 0.2mm. Do not use support.
Afterward ensure that the edges at the bottom do not stick out (due to the famous elephant foot).

Print the rock with a dark PLA or PETG type that will still reflect light (so no black). I used gray PLA for this. To make the surface of the rock a little rougher I used a slight fuzzy mode, but that is not required.
Again I used a nozzle of 0.4mm and a layer thickness of 0.2mm. Don't use support here either.

Needed Parts

To illuminate the crystals (9 in total) I used 5mm slow color changing LEDs. These are very readily available and not expensive.
Make sure that you do not use bright LEDs, but diffuse (fog) versions, otherwise the light will not be spread evenly through the crystals.
Each LED illuminates 1 crystal and this light also remains in this one crystal due to intermediate walls.

Placing and soldering the leds

There are 9 holes of Ø5 mm in the bottom of the crystal insert. Place an LED in each hole.
I placed the anode (-) pole of the LEDs facing inwards and bent them towards each other in the shape of a circle. I then soldered all the anodes together.
I bent the cathodes (+) pole a few mm above the bottom surface of the crystal insert to the cathode of the middle led and I also soldered these together.
A small resistor of at least 10 Ohm must now be added. You can also choose a resistor with a larger value to make the LEDs shine less brightly.
The resistor can be soldered to both the cathodes and the anodes. I soldered them to the anodes.
Now a USB cable needs to be soldered to it. I used a cord that I still had lying around and cut off the micro-usb plug. The red wire should be soldered to the cathodes and the black wire to the anodes. Use some insulation or tape to prevent the + and - circuits from touching each other.

Now place the crystal insert in the rock (this fits exactly) and clamp the USB cable (Ø3.5mm) in the channel printed for that purpose in the bottom of the rock. Secure it with a little glue.

Use

Connect the USB cable to a USB power supply.
The LEDs will now start simultaneously with the same color!
Because there are milliseconds difference in the glow frequency of each individual LED, they will get out of sync over time and a random color pattern will arise.
The color changing frequency for each individual led is typically around 3-4 seconds. This creates an ever changing overall glow.

Update (09-03):

I added a Base Raiser (20mm) as STL and as STEP so that if you want to use battery power you can make a recess for the used battery holder. A small raised edge has been added which fits exactly into the square recess of the original Rock Base. Use either negative volumes in the slicer (don't scale, otherwise the centering won't work) to make the recess, change the height and so, or the shared step to create your own solution.

p.s. fill the original hole for the cable entry so that no light "leaks" through that hole.

Update (21-03):

I have added a rockbase with extra clearance for the Crystal Insert. This will make it easier to place it in the cut-out.