How to develop a simple pressure sensor?

The main material is velostat

and two conductive materials to make it like sandwich

This is capacitance concept

Capacitance is the ratio of the change in an electric charge in a system to the corresponding change in its electric potential. 

Pressure sensor video

How to setup ESP32 in Arduino IDE?

Open Arduino IDE

Select Preferences or shortcut (control + , ) / (command + , )

Copy and paste this url address into add board url

https://dl.espressif.com/dl/package_esp32_index.json
Then, open board manager, search esp32 and install
Wait until download is finish...Done

Alternatively, open this url
https://github.com/espressif/arduino-esp32
Clone zip.file into your computer
Upload to Arduino IDE...Done