• The RFID Communications Node.
• The Display Node.
• The Locking Node.

An Arduino Uno read and authenticated RFID signals. The results were communicated to the Arduino Nano, which used a radio module to send the results to the Raspberry Pi. The second Arduino also controlled LED authentication indicators.
The hardware used consisted of an MFRC522 contactless RF reader, an NRF24L01+ radio transceiver, and Arduino Nano, an Arduino Uno and two LEDs with resistors, as can be seen below.

My Raspberry Pi read the incoming radio signal from the RFID Reader node. It then decided to toggle the lock state or not, and sent a signal to the Locking node. Simultaneously it ran and updated an API-powered GUI showing data of interest.
The hardware consisted of a Raspberry Pi Model 2B, an NRF24L01+ radio transceiver module, a 13” laptop LCD display and a laptop controller board.

The simplest of my 3 nodes. This node consisted of an Arduino Uno attached to a motor power board, a stepper motor and a capacitive touch button. The Arduino would toggle the lock state based on input from the Raspberry Pi and the button attached. Then it would rotate the motor a specific amount to open/close the lock.
The hardware consisted of a 3D printed lock mechanism, and Arduino Uno, a TTP223 capacitive touch sensor, a stepper motor & motor power supply board.