Use 'rough out' when you start planning something but aren't adding details yet.

Initial Planning

'Rough out' implies you're in the brainstorming stage, not the final stage.

Brainstorming stage

A plan 'roughed out' is not binding, and is expected to change as it develops.

Use 'rough out' to describe the early phase of crafting or shaping a material.

'Rough out' suggests the result is unfinished and not smoothed out or perfected.

It indicates preparatory work's been done before final touches are applied.