Introduction: Cheap Music Reactive Light Show

About: We are two brothers who like to make things.

This is one of the easiest ways to make a music reactive light show!

It work by modulating laser light using a reflective diaphragm/membrane made from mylar that is moved by sound waves coming from a speaker.

There are two versions here in this instructable; one quick non-motorized cardboard version, and a motorized version that adds additional movement using a motor and also has more advantages.

Step 1: Beware!

Don't look directly into the laser pointer! Eye damage may occur if you get direct eye exposure.


Laser responsibly!

Step 2: Acquire Parts Needed

Green Laser Pointer

Metallic Survival Blanket

Cardboard rectangle 3 by 8 inches or 76mm by 200mm

2 AAA batteries

For the motorized version, you will also need:

Geared Motor -We used the specific model in the link

2mm drill bit

1/2 inch drill bit


One block of wood 3 inches wide by at least 5 inches long by at least 1/2 inch thick or 76mm by 127mm by 12mm.

Rubber bands

Empty tape roll (any sort of rigid cylindrical ring will work)

2mm diameter bendable/stiff wire from salvage or clothes hanger.

Hot glue gun

hot glue sticks

One LR44 button cell battery

One Zip Tie (cable tie)

Snips or Pliers.

Step 3: Quick Version

The quick, non-motorized version made by simply puncturing holes using the pliers in the cardboard along a line, then widening the holes to fit the laser pointer snugly.

The reflective piece of mylar is just wrapped or taped over the speaker grill.

You can adjust the angle of the laser by moving the laser to a different hole.

The laser ON button is simply pressed down by the cardboard.

Step 4: Motorized Version

The rest of this tutorial will show you how to build the motorized version, which has better features than the quick cardboard version.

  1. The motorized version can produce different moving light patterns that the quick version, such as a green flame illusion.
  2. The motorized version is more adjustable, because it uses bendable wire.
  3. The motorized version doesn't not require the mylar diaphragm/membrane to be fastened onto the speaker itself. This allows you to move the diaphragm farther away from the speaker to change the intensity of the light show without sacrificing volume.

Step 5: Drill the 1st Hole

Using the 1/2 inch drill bit, drill a hole through the wood block 3/4 to 1 inch from the end of the block, centered.

The should be one video attached per each step!

Step 6: Smooth It Out

Use the 2mm bit to smooth out the edges of the 1/2 inch diameter hole.

Simple scrape the bit around the edge both directions while the drill is spinning.

Take care to avoid snapping the bit!

Step 7: Drill More Holes

Using the 2mm bit, drill a hole halfway between the 1/2 inch diameter hole and the end of the block as shown.

Then, drill one more hole on the opposite end of the block.

Step 8: Drill a Hole in the Tape Roll

Drill a hole in the empty tape roll as shown using the 2mm bit.

Step 9: Make the Reflective Drum

Cut a piece of mylar to the size you need to wrap it over one side of the empty tape roll.

Wrinkling the mylar before flattening it will give it the decorative pattern it reflects on the wall instead of just acting as a regular mirror.

Pull the mylar over the tape roll, and use the rubber bands to hold it in place.

Step 10: Preheat the Hot Glue Gun

Plug the hot glue gun into a wall outlet so it can start to warm up.

You are ready for the next step once the hot glue starts to liquefy and drip out the nozzle.

Step 11: Glue the Wire Onto the Diaphragm.

Press one end of a 7 inch long piece of wire through the hole previously drilled in the empty tape roll, and glue it in place with the hot glue.

Hold it in place while it solidifies!

Step 12: Cut a Strip of Zip Tie

Using the pliers' cutting edge, or a snip tool, cut a 3/4 inch to 1 inch long strip of zip tie.

One end needs to be cut diagonally. This piece forms the slipping arm that flicks wire which holds the laser, making it sweep back and forth when you want the motor to be on.

Step 13: Glue the Zip Tie Arm 1/3

Add a dab of hot glue onto the flat side of the arm near the end and let it cool. This is done over three steps instead of glueing the arm directly onto the motor because it will not stick if done in one step.

Step 14: Glue the Zip Tie Arm 2/3

Add a dab of hot glue to the head of the motor and let it cool.

Be sure to avoid getting glue on the non-moving parts of the motor, or else the moving part will be fused and prevented from moving!

Step 15: Glue the Zip Tie Arm 3/3

Add a dab of hot glue onto the old dab of hot glue on the motor head, and stick it to the old dab of hot glue on the zip tie arm. This fastens the arm to the motor.

Step 16: Fasten the Reflective Component to the Wood Block

Stick the reflective drum component wire into the farthest hole you drilled in the wooden block, and glue it in place.

Step 17: Make the Laser Holder Component

Wrap the end of a 12 inch long piece of wire around the laser pointer away from the button or light opening to form a coil, then slip it off.

You need the leave at least 6 inches of that piece of wire straightened.

Step 18: Glue the Laser Holder Component to the Block

Stick the laser holder you just made into the 2mm diameter hole closest to the 1/2 inch diameter hole, and glue it in place.

Step 19: Add Batteries!

Put 2 AAA batteries in the laser pointer with the positive ends towards the butt of the laser pointer.

Put the LR44 button cell battery into the motor's built-in holder. The part of the battery with engraved writing on it goes outwards.

Step 20: Stick the Motor Component Into the Last Hole

Gently press-fit the motor component into the 1/2 inch diameter hole, leaving the switch accessible.

Don't press it in too tight or else you won't be able to remove it to replace a battery when you need a new one!

Step 21: Set It Up!

Put the laser point in the wire coil holder so that the button is held down.

Adjust the angle by bending the wires so that the laser beam reflects off of the mylar, and hits the ceiling or wall in the general direction you want it to aim.

Start the music and move the whole assembly close to the speaker!

You can adjust the distance as you like.

Don't let the laser light hit anyone in the eye directly or by reflecting off other objects in the room! Lasers can cause blindness!

Step 22: 3... 2... 1... PARTY!

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