Solved! Go to Solution.
I have created a C# project with some commands and tools and an associated toolbar. I want to share some data among these items within the project (so that the data is available to each tool or command when it is executing)
All commands, tools and the toolbar are in the same project, which is an add-in (to be implemented via Tools/Customization). As to design patterns, right now I have no choices - as I said, I am stumped, but I think I am missing something really obvious...