You can make a copy of any board you have permission to access, including your own personal boards and any boards that other authors have made public. Copies will maintain a link back to the original board for attribution purposes.
Copying someone else's board
When you are looking at someone else's board you can hit "Make a Copy" to copy the user's board. This will make a new copy owned by you that you can then change as you would like.
Copying your own board
You can also make a new copy of a board you already own if you want to make additional changes or test changes to an existing board before making them official.
If you try making a copy of the board that's currently part of your vocabulary set, CoughDrop will ask if you want to swap out the new copy for the original in your communication set. Note that this can potentially make copies of every board in your vocabulary set, since it also will need to update any links that point to the modified board.