Sometimes it can be very tedious having to go into the context menu for various objects in order to set shapes and shape conditions. It would streamline building a LOT if we could "paint" these properties onto objects with a dedicated tool. Copy/paste helps in some situations, but not always.
In fact a good solution to this might be to just add a tab to the parts menu for Properties, where you can select not just shapes and shape conditions, but other properties like wings, balloons, and explosions, projectiles, and common part conditions.