I'm still putting together my 1st PSK in an altoids tin and appreciate everyone's input here.
For a signal mirror, I purchased a lightweight signal mirror, which is really just heavy plastic. I cut it to the size of the tin cover, put a peel away sheet on to protect it, and attached it to the inside of the lid with a small peice of double stick tape. It is held in place firmly, but can also be peeled off the cover for use so I don't need to worry about the tin spilling when I signal.
Any thoughts on better ways to do this are appreciated, and thanks again!
-Dave