Another project I had always in my list is to make a little radio with an amplifier, a speaker, a battery and an FM module. Let's see what you could make with a little inventiveness, a few cheap modules, a 3D printer and a few tools.

Step 1: The Modules

Some years ago I bought a cheap small 2W speaker, and after a few time the rubbery plastic became sticky and I dismantled it to throw away its case. I kept everything else and the battery still works good. That speaker has a jack as well as a 3.5mm plug.

As synthesizer I bought a digital FM module, it's nice to see and has two rotary encoders to set syntony and volume.

Step 2: A Few Addons

You also need a bigger on-off switch, an antenna, two knobs. You can choose this material to personalize your device as much as you wish.

Step 3: The Sketch

To avoid any problem and mistake, I always suggest you to draw a fast sketch by hand, after taking all the measures needed. This will be very useful to make a design with a 3D software.

Step 4: The 3D Model

I designed the case with Rhino3D, but you can use any 3D software, from openSCAD, FreeCad, SketchUp, Blender, to Thinkercad. Some are free, other are commercial, but they're not expensive, and all are good to model a case for your devices.

I attach three .stl files, which are the case, the bottom cover, and the support for my switch, which can be different for your switch.

Step 5: Time to Print

With my Tronxy 3D printer, a small, cheap and old but very good printer I bought years ago, I made all parts I need. I had to let the slicer adding some supports, which are annoying but sometimes necessary.

Step 6: Finishing

After removing every supports, I sanded surfaces and checked the dimensions so that parts fit together. I had to file and reduce some edges, but after some work everything fits, also the FM module, having rounded its corners, enters in its seat. A piece of electrical tape will avoid short circuits.

Step 7: Wires

As you see I had to solder some short wires, to extract LED and switch from the plate, and so that the speaker Li-Ion battery will power the FM module too. The antenna and the audio jack will exit from little holes.

Step 8: Fit Everything

Everything fit in seat, the round circuit board wedge in between the holes, so that it doesn't need to be glued. The switch support is glued to the ceiling, and a piece of plexiglass is glued on it and to the wall, to reinforce the connection.

Step 9: Close It

The bottom lid only needs two screws, since the front side will slide inside the edge. I added four rubber feet, to avoid slipping.

Step 10: Turn on and Enjoy

As you see the rear mini-usb socket will charge the radio battery, and you can also hear the music in the while.

If you take out the jack, you can insert your earphones there. And you can connect another device with another audio jack in the other socket, to hear any other audio source on this speaker. It's also quite powerful, as it uses a neodymium magnet.

I hope you can build your own radio following my advices. Please write any your comment below.