3D-printed USB-powered AAA Batteries Substitution

My son built his own mechanical keyboard using parts he ordered online, following his older brother's footstep. It works well (powered by 2 AAA batteries) but it doesn't shut off automatically when not used (has a manual on/off switch) so every several weeks, he'd go around the house looking for a fresh set of batteries. I bought him a rechargeable AAA batteries and it seemed to work initially until one day he complained that the keyboard sometimes responds erratically when he plays Valeran (double-up on a key he typed 1x, or delays) and I figured it may be because of the rechargeable batteries supplying only 1.2V instead of 1.5V like normal battery. Browsing online, I saw an arduino module for DC voltage step down (adjustable using potentiometer) and with a 3D printer, I thought I could dummy up a USB-powered AAA batteries needed for the keyboard. The only catch is he won't be able to use the keyboard's battery cover anymore.

This is a relatively easy project with very few requirements and no programming required!

1. Arduino Compatible DC Voltage Regulator Module
2. Cables suitable for Arduino modules
3. 1x LED (3V)
4. 1 cable with female USB plug (type-A) for output of DC Voltage Regulator Module - this is black cable in my project here
5. 1 cable with male USB plug (type-A) for input to DC Voltage Regulator Module - this is white cable in my project here
6. 1 cable with male USB plug (type-A) to power the dummy batteries from DC Voltage Regulator Module - this is also a black cable in my project here

Connect the DC Voltage Regulator Module with a standard, simple, USB power source like powerbank (any size, as long as it can supply 5V) as the input. Check with multimeter the output, and adjust the potentiometer (blue component on the Module) accordingly (left turn or right turn) so the output is 3V (or just above; I think fresh battery can do 1.55V so I set mine to be 3.09V).

1. Solder the (white) male USB male plug cable to the input of DC Voltage Regulator Module, GND to (IN -), 5V to (IN +).
2. Solder an LED to the output of DC Voltage Regulator Module, to indicate that the module works and generates output. Mindful of the (+) and (+) of the LED, connect to the correct output terminal of the Module.
3. Solder the (black) female USB output wire to the Module (one to OUT +, one to OUT -).

Download the attached STL file to 3D-print a dummy AAA battery (my printer is Creality Ender 3 V3 SE).

Expose the wire of GND USB male (black) cable and attach it to one end of the dummy battery. Do it again using the other wire (for +3V) for the end of the other dummy battery.

Using multimeter, measure the end of the two "batteries" and it should read +3.09V.

Mindful of how the batteries are setup in the keyboard, insert the "batteries" as required. They should fit nicely, both diameter and length of the "battery" should be similar to the real AAA battery.

Connect the project to any USB output and fingers-crossed, it all works. I have a failed 3-D printed earphone container, which fits the Module somewhat nicely, so I drilled hole at the top for LED, created a notch at each side for the input & output of the Module and secured the cables with glue gun.