3M Co. is showing off a two-year redesign of its headquarters, the first facelift the manufacturer had given to its dated public areas since the 1960s. The Pioneer Press has an extensive story on the multiyear project, which introduced more open spaces, collaboration areas, and retail areas (Starbucks and U.S. Bank (NYSE: USB) both have spaces) to 3M's midcentury-era Maplewood offices. There are also plenty of photos, as well as some discussion on what was at stake for 3M: employee needs and habits…