I found this cheap old classical guitar sitting in my storage, deformed and unplayable, so I decided to turn it into something more than a decoration.

Step 1: Preparation

Tools I use for this project:

1. Jigsaw. (Cut holes on the guitar)
2. Drills. (Drill holes for the power and 6.4mm jack).
3. Screwdrivers. (Disassemble amplifier).
4. Torx screwdriver (Disassemble amplifier, depends on the model you got).
5. Soldering iron. (Solder speakers & rewire onboard power and audio input).
6. Desoldering pump.
7. Scissors (Cut the wire).

Step 2: Choose Your Speakers

Go search for the right speaker for you on the internet, I'm using a set of 4" Full range 8 Ohm speakers. I found this set best suited for the color and style of the project.

Step 3: Choose Your Amplifier

Again you can search the internet for the amplifier suitable for this project. I choose Lepai LP-A68 amplifier as it resembles the volume control panel on electric guitar. You can find it on Amazon: https://www.amazon.com/s/ref=nb_sb_noss_2?url=sear...

Step 4: Get Other Parts

1. 6.4mm phone jack: https://www.alibaba.com/trade/search?fsb=y&IndexAr...

2. Female DC power jack: https://www.alibaba.com/trade/search?fsb=y&IndexAr...

3. Guitar jack plate: https://www.alibaba.com/trade/search?fsb=y&IndexAr...

Step 5: Make a Plan

1. Take your time and plan where to put your speakers, amplifier, phone jack and dc input.

2. Measure and draw the cut lines.

Step 6: Disassemble the Amplifier and Rewire

1. Solder the wires connects to phone jack and pcb board.

2. Solder the wires connects to DC female jack and pcb board.

3. Insert the speaker wires to both channels.

Step 7: Cut Holes and Assemble Everything

Test connections and make sure everything fits in.

I did an awful job cutting the guitar, but it'll look better once it's assembled.

Step 8: Adding Bluetooth

Some amplifier has built-in Bluetooth, but not this one. The easiest way to add this feature is to get a Bluetooth audio dongle since LP-A68 has an USB port. BT dongle: https://www.alibaba.com/trade/search?fsb=y&IndexAr...

Step 9: Done!

You can use a guitar cable and a 6.4" to 3.5" audio converter to plugin your audio device, or you can use two short converter to make your phone "stick" on the guitar speaker (as shown in the pic). I also use a leather strap so I can hang it on the wall. I plan to add a chargeable battery inside to make it cordless.