Putting everything together – think of a protective case for the project!

This section shows how you can place the electronic circuit with the ultrasonic sensor inside a protective case. The section also shows some suggestions on how to fit everything in a plastic or glass container, because if you use the 20-second counter in a bathroom or in a place close to a hand washing sink, you will need to protect the circuit against water spilling and soap stains that can damage the electronic components used in this 20-second counter project. We do not recommend you connect the Blue Pill board to a wall USB adapter for security reasons. It is best to connect the Blue Pill to a USB power bank.

If you can't fit the whole 20-second counter circuit (including its solderless breadboard) in a plastic or glass container, try connecting the Blue Pill on a smaller solderless breadboard such as a half breadboard. Detach the ultrasonic sensor and the LCD from the breadboard and position...