Master shelf populated by checkbox, rather than switching
The master shelf is a one stop GUI element that can gather shelf buttons from any of your shelves in one place.
Right click the master shelf, and check on which shelves you want to borrow icons from. They then appear in the master shelf with a spacer between them. Ideally, the spacer shows the name of the shelf and a cross to hide it.
This is a neat way to show, for example, geometry and one or more of your custom shelves at the same time.