I think there are a few ways to do this, but the general steps are:
- Add a PME TOOLBAR
- Hide the 3D Toolshelf Defaults
- Add desired Toolshelf Panels
Here’s a similar example: https://bit.ly/2LqsjEA
The name of this toolbar is called “Toolbar Top”.
You can add more buttons to the toolbar there.
Be sure to add a toolbar above the 3d viewport using the following steps:
1. Split the 3D viewport window horizontally,
2. Change the new window to a User Preferences window.
3. Minimize this new window's header.
The Blender icon button toggles the default toolshelf tabs.
The plug icon button hides 2 addons. ( Looptools & Oscurart Tools. )
The modifier wrench button has custom panels. ( Modifiers, Set Origin, and Snap. )
I hope this helps.
Good luck. ^^