This is my modification of the awesome PKE Meter by hobbyman.

https://www.youtube.com/watch?v=xTfZLYqommg

My changes were done to accommodate the electronics and to simplify the design for my 7 year old son. I scaled the whole model up to 110%, added a screen holder for a 0.96" Inch LCD LED Module 128X64. I removed the top three buttons and designed it around a 2 button input method for a kid. I also modified the battery area to accommodate the 4 AAA's to power all of this since it was scaled up and the area was too big now.

No buttons pressed it is in the idle state. When button one is pressed and held it is at 50% and button two at 100%. This has worked very well for my son.

The electronics are based off an arduino nano with a custom PCB fabricated by OshPark. You can find the arduino code, pcb schematic, and brd files in my github repo here:

https://github.com/CountDeMonet/Arduino_PKE_Meter

The full parts list:

• Arduino nano clone
• Buck converter to power the servo at 5v
• Diymall 0.96" Inch Yellow Blue I2c IIC Serial Oled LCD LED Module
• A micro servo of your choosing. I used a bluebird that I had laying around
• Cheaper to get the rest in a starter kit from amazon. I used:
  -- 2 buttons
  -- 7 220ohm resistors
  -- a buzzer
• 14 3mm Yellow LED's I bought a ton of led's a while back for other projects.
• one on/off switch I ripped out of one of my sons dead toys

I printed mine at .3mm resolution with a 20% infill with supports. This print requires a lot of supports but it is worth it. I wish I would have printed at .2mm resolution but my prototype has become the one my son will use.

I have included the buttons_filled.3mf file in case you need to adjust the spacing for the buttons. I built my own input board for two standard buttons from an arduino kit. If you choose something else you can modify this file to work with it.

Update 8/18/2017
I needed a belt holder for the meter so I modified the one daniel_nelms made to fit this one and reduced it in size a bit.