The shape

This study uses a continuous ribbon to describe an open volume. The helix widens through the middle and narrows at the top and bottom.

In Houdini

A Sweep node carries the ribbon along the helix. The ribbon also twists along its path, and a PolyExtrude node gives it thickness.

In Unreal

The geometry was exported as FBX and placed in a test scene. The still above shows the result on a plinth, with its cast shadow.

Part of a procedural sculpture study.