This is a fake bomb made from the cardboard tube from a roller blind.
Step 1: The Bits
Step 2: The Build
Cut the tube into 4 equal lengths, I used Magenta ink from a refill kit to paint them.
Cut the wire into 4 , fit them to the end caps.
Strap the sticks of TNT together with tape.
Stick the timer over the end of the wires.