Introduction: Relaxing Sounds BOX (motion Sensitive, 3D Printed)

About: Mechanical engineer. Hobbyist in Arduino, 3D printing, android Apps, Geocaching, Cooking, Woodwork, CAD, software coding... Willing to learn and interested in many things :)

A walk in the forest is a power boost for well-being and health. The rustling of the leaves in the wind, the chirping of the birds... just relaxing.

Unfortunately, nowadays we have less and less time for an excursion into the soothing forest. This gave my wife the idea to bring the atmosphere of the calming forest into our home. A box that fills the room with birdsong when we come home and lets us hear the leaves rustling as we walk through the house.

Well, of course you can play all the sounds you want with the box, so if you prefer to relax with metal music, feel free. :)


The links goes to the sites/products I used, don't be surprised: most of the sites are german :) You don't need to take exactly the products from the linked sites. This is only a help to show the necessary product.


The Box:

You can create the box with the material as you want. In my case, I printed the back of the box (including the battery holder) with a 3D printer and for the front I used a wood panel. My materials for the box were:

Battery Holder:

You need a battery holder for 4xAA or 4xAAA batteries in the Box. If you have already such a holder at home, you just have to mount it later to the case. I made one by myself, That's what the materials were for:

  • 3D printer (filament)
  • Sheet metal as contacts
  • Wires


  • Soldering iron
  • Precision screwdriver
  • Wood glue
  • Jigsaw
  • Drilling machine
  • Metal scissors (just if you make your own battery holder)

Step 1: Creating the Back of Your Box

As mentioned, you can create your Box out of whatever you want or what is available to you. Be creative, I'm looking forward of pictures of your individual boxes :)

Anyway, here is the way I made it:

First, I designed the back of the box in a CAD Software. I needed a model to feed it to my 3D printer.

In my design, the electrical components can all easily clipped in, so I don't need any glue and it is possible to remove the single components if anything will happen. Or for disassemble. Who knows :)

The battery holder is also printed. See next step.

On my design of the back is a cutout for a On/Off switch and a cutout for a volume regulating wheel. The switch can easily plugged in it. For the volume wheel, I designed a simple ribbed wheel with the inner diameter of the potentiometer.

I provide the STL files for download. If you like, and you have a 3D printer, you may use it for your box. If you have different electronic parts than mine (which seems likely, especially the switch and the potentiometer), you have to modify it to your needings.

If the design is ready and fits to your components, it is time for printing!

If you want it more colorful, paint the box :) I decided to paint it in a plant-green.

Step 2: Create Battery Holder (optional)

This step is just necessary if you don't have a finished battery holder at home. If you have already one, you just have to mount it on your case and you can skip this step.

I simply used the battery holder which I found on thingiverse, here. You do not have to reinvent the wheel if it already exists :)

On thingiverse, the author took this clamps for the contacts. But I decided to create my own ones with the stuf I already have at home. (Honestly, if I would buy the clamps, I could already buy a complete battery holder too). I used little, thin pieces of sheet metal which I cut in the right dimensions, bent it, and plugged it into the battery holder as contacts for the batteries. Double check if the batteries hold in the box, or if you have to rebend it.

On the back of the holder I wrapped the wires arount the metal and bent the metal to the ground.

Tip: You can fix your wires with super glue in the holder if you want.

Step 3: Creating the Front of Your Box

For the front I used a wood panel. I printed the drawing of the front from the CAD software on paper, cut it out, and fixed it with tape on the wood panel. Then, I used the jigsaw to bring it to shape.

After the wood was saw into shape, I used the print of the front again, taped it on the wood, and used it as a stencil for the holes. I used a simple hand drilling machine for the holes.

Tip: Don't use too much force at drilling, the wood could tear out.

You can make the holes for the sound in the size and form as you want. But the diameter of the hole for the motion sensor is very important! Make it the same diameter than the sensor. In my case, I used a 8mm drill. Then the sensor can easily plugged in and sticks in the panel.

Tip: If your sensor doesn't stick in the hole, use a little dot of wood glue for fixing it.

The front will be screwed fix through the back of the box. For giving the screws more material, use the rest of the wood panel, saw it to small pieces and glue it on the edges where the scews hold the front. So the wood panel is thicker for the screws and they will not come out on the front, which would look realy... not good :)

After the sawing and drilling, you can grind the panel to make it smoother. If you want it more colorful, than paint it :) I myself oiled it with furniture oil. Comes out great :)

Step 4: The Microcontroler Part


For bringing the Box alive, I used an Arduino Nano. To provide the power, I decided to simply use a battery block of four AA batteries, so you can put the box wherever you want and don't need to plug it somewhere in. For making it motion sensitive, I used a PIR sensor HC-SR501. You could also use a 505, but the 501 has the possibility to adjust sensitivity and duration of his signal.

I designed the case in a way, that I could plug/clip the parts in the box. The battery holder is screwed with four self tapping screws. Just plug the speaker, the potentiometer and the switch in the case. The Arduino and the DFPlayer mini as well. Remove the white hemisphere from the motion sensor (Attention: Don't touch the front of the sensor, it will make his function worse), and plug it in the 8mm hole in the front wood panel. Then, connect the parts.

I added a drawing of the circuit here. For connecting the single components, I primary used jumper wires (F-F) which are able to plug it on the pins of the components. With some components it is not possible, there I soldered the connections.

Tip: Instead of using a potentiometer AND a On/Off Switch, you could just use a Switch Rotary Potentiometer. It has a switch in end position, so you have two parts in one. I just didn't use one because I haven't had one at home.


The Arduino code is very simple. Beside the common libraries you may need to download and install the DFPlayerMini_Fast.h library (Github Link). Then just copy my code into the Arduino IDE and upload it to your Arduino. I added it to this step.

If you took different pins than the one on the scetch on your arduino, you may need to adjust these in the code.

Important: When you have already powered up your Arduino with the batteries, then you always have to turn the switch OFF when you connect the Arduino to your computer to write data on it. It’s very important NOT to connect a USB cable the same time with the batteries, because your Arduino board is already powered!

The Sounds:

The DFPlayer mini needs the sounds as mp3 files. They must be stored on your micro-SD card in a folder named "mp3", placed under the SD card root directory. The mp3 file name needs to be 4 digits, for example, "0001.mp3", placed in the mp3 folder. If you want to name it more recognizable, you can add a name after the number, for example, "0001Bird.mp3". But don't use spaces in the filename, this may couse problems.

Where to get the sounds? Well, I used the www and downloaded some nature/bird sounds. Because some of the tracks are much longer than 2 or 3 minutes, I cut them in single tracks. For this I used Audacity software, but any other audio cutting software will do this job, too.

I figured out that a track length between 1 to 3 minutes are fine for my use.

Step 5: Final Assembly And... RELAXING

If not already done, screw the battery holder to the box. Then, assemble all the electronic stuff inside. The Arduino Nano and the DFPlayer can be clipped in, the potentiometer, the switch and the speaker can be gently pushed in. If they will not hold in their forms, use a little dot of super glue.

If everything is on its place, push the motion sensor in its hole in the wood panel.

Close the box, and use your precision screw driver and 5 self tapping screws to screw it together. Keep attention, the screws should not be too long to come out of the front.

And that's it! Switch it on, move yourself, and listen to the birds :)
I realy enjoy it when I come home and am greeted by the discreet twittering of birds. Very calming for me.

Step 6: Possible Improvements/Additions

As mentioned, one improvement would be to use a switch rotary potentiometer, instead of the two single components I used. This simplifies the operating a little more. But honestly, I think a volume wheel and a button is not the hardest operating panel these days :) It also has the advantage that the volume does not have to be adjusted each time you switch it on.

A more useful improvement would be:

I'm thinking of the situation when you are sitting in your armchair, and reading a book. I could imagine that some relaxing nature sounds sometimes would be nice while reading. Well, at the moment, you have to move yourself regulary when you want the box to play some background sounds. So, kind of a button or something to turn the sounds steadily on and keep it playing till you hit the button a second time would be nice, but was not necessary to my needs.

Another additional idea:

In these days, eveything comes with LEDs on it (even hats, check out my first instruction). It is not hard to add a RGB LED inside the Box, maybe which changes color regulary. So the speaker holes would shine in a nice colored light. For this I would recommend a WS2812B LED with the FastLED.h library for coding it.

Rethinking of the DFPlayer position:

After the first few days of using the box, I'm rethinking of the positioning of the DFPlayer module. The reason is the micro-SD card. In the first days, I added a few new sounds to the card, and therefore it is necessary to disassemble the front. It would be easier to get the card without disassembling it. It would have been more comfortable to add a cutout on the side for the SD card and reposition the DFPLayer module.

And you? Do you have any more ideas for this relaxing box? Tell me, and maybe I will do a second version of it :) Thanks for reading! Have fun with tinkering!

Audio Challenge 2020

Runner Up in the
Audio Challenge 2020