The main components of the build are:

• Stomp Switch: The main component, typically used for effect pedals. Its spring is strong enough to send the lever flying when the pin is released, as the lever in a real grenade would. Also, being a switch, it sends a signal to the Arduino Nano that the lever is off.
• Arduino Nano: runs a simple script that:
  • gets as input the signal from the stomp switch.
  • starts a random fuse timer between 2.70s and 3.30s, to simulate real world fuse errors due to humidity.
  • when the timer ends, it lights 4 LEDs on the outside and starts the buzzer to indicate the explosion.
• 9V Battery: Li-Po or Li-Ion Batteries can also be used but they could be a hazard in hard impacts.
• On-Off Switch: Located at the bottom of the grenade, inside a recess, it turns on and off the power supply to the Arduino.
• 3D Printed Shell: Ideally it should be printed in TPU for maximum strength and impact protection. It is split into 2 pieces that are kept together with 2 screws. Sand can be added in the inside to add weight, hence making the grenade feel more "real". As an added bonus, sand will also prevent the internal components from bouncing around and getting damaged. The STEP and STL files can be downloaded below.
• Lever and Pin: The lever needs to be stiff so PETG or Nylon are great materials for this. The pin is made from a bent paperclip and the ring from a key chain. The files can be found on Thingiverse, in the page of the original design that this project was inspired from.