Modular Trireme: Cargo expansion

This is an expansion for the [Modular Trireme set](https://www.thingiverse.com/thing:7139559).

Take your modular ship to the closest harbour! You now have cargo to store, sell... and possibly lose to pirates.

These cargo sections fit inside the modular ship. The set contains a stack of amphorae and sacks of grain to fit in the back of the ship, a covered pile of grain (or gold?), and two inserts that fit into the lowered storage in the middle of the ship. The optional 'back slider' can be glued to the back insert to more securely slot it into the lowered storage.

- Sections sized for 1" grid compatibility.
- Designed for and tested on an FDM printer