In this video, analyst John Reeves looks back on one of the Fool's pieces on the market's top 10 stocks of 2012 and notes some important trends for investors to take away. John tells us about the housing recovery trend we saw in 2012 that buoyed several different sectors with links to housing, and gives us three key companies that really took off in 2012 as a result. He also discusses the 3-D printing revolution and the two big names in 3-D printing, Stratasys (SSYS) and 3D Systems (DDD 1.33%), which tripled, or even quadrupled, investments in 2012.