Steampunk - Altered Book Cover

I started by collaging papers on the cover and adding leather to the spine.  In the center of the book is a vintage mailbox door.  I cut a hole in the cover and in the first several pages of the book in order to insert the door.  The mailbox door and combination work or would work if I could remember the “safe place” where I put the combination.  The larger gears are rusted chipboard.  To see the tutorial on rusting objects click here.  I haven’t done anything to the inside of the book.  I think I’ll just use it for décor.