UI to select different tools for right and left click

I’m working a specialized paint web application (for designing Minecraft structures). I would like for the user to be able to assign different tools to the left and right mouse buttons. (I don’t intend to override the default right-click behavior other than this.)

I have a traditional tool palette. I’ve been experimenting with a way to indicate that the user has selected one tool for the left mouse button and another tool for the right mouse button:

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The left and right tool indicators are differentiated in three ways:

  • Position (left vs right)
  • A tiny L or R.
  • Contrasting (though meaningless) colors.

In order to select a tool, the user clicks on the tool icon with either the left or right mouse button, and that button will be bound to that tool.

The right-click tool functionality is (very) convenient, but not essential. Users who can’t or don’t want to right-click can use the left button exclusively. In addition, when the cursor is over the canvas, then the appropriate cursor icon for the left tool will be displayed unless the user is actively using the right tool.

Does this UI make sense? I’m not nearly at the stage of user testing yet, but I wanted a sanity check because I don’t think I’ve seen this pattern before. An alternative would be to have a separate tool palette for right clicking, but I’m concerned that this could be confusing and inconvenient.