Version 2.0 rebuilt from scratch using this as a guide. Improved pillars, lid and locking mechanism. The new design has been uploaded as a remix.

Parthenon model with a hidden box. The base is split into 3 parts for easier printing. Print 2 of the catches and slot them into the middle piece, sliding them to the right will unlock the lid. Remix of a Parthenon design on GrabCAD: https://grabcad.com/library/parthenon