Introduction: Checklist
This project I use this person as a reference https://www.instructables.com/id/Random-Machine/.
I use this as a checklist for triathlon.
Step 1: Prepare
Step 2: Circuit
Step 3: Source Code
https://create.arduino.cc/editor/ChiehLiu/962bd325-98b0-44d9-83b8-a379a0b3fec8/preview
Step 4: Decoration
You can find a box and put your Arduino inside the box and use the utility knife to cut out the place to put LCD and the button.