This is a simple model of the plutonium core used in the Trinity nuclear device. Printed out it gives a good understanding of just how little plutonium it takes to destroy a city.

There are three components:

1. Initiator Core - solid beryllium coated with gold and polonium.
2. Urchin - Hollow beryllium with grooves cut inside, nickel plated with grooves coated with gold and polonium.
3. Core - 6.19kg plutonium.

Also included in the scad file are other trinity device components. These are all still works-in-progress.

Thanks to John Coster-Mullen for his great book "Atom Bombs: The Top Secret Inside Story of Little Boy and Fat Man".

Print two of each item. Glue together the initiator core. Fit the urchin halves over the core. Place the urchin in the pit in the plutonium core. (The gap in the real one was filled will gold foil.) Place the other plutonium half on top. Don't squeeze too hard.