In assisting another colleague building new 2012 servers for a software installation that requires Dot Net 2.0 and 3.0 the Add Features utility required the 2012 install media.

Great write up to get this done on Spiceworks.

Oddly, in another 2012 Server build the adding of Dot Net 2.0 and 3.0 from the Features wizard worked perfectly and did not require additional media to be added.

UPDATE: I think I need to retest this, because when I did this a second time, I may have left the ISO in the drive which maybe caused the Roles and Features window to not prompt for an install location.