Last week I purchased at Artstation "Concept Masters Volume 4".  Sebastian Luca uses Photoshop, 3DCoat and Keyshot to produce some really neat comic book like line art images. Although I did not learn much about 3DC, I really enjoyed watching the video and opened my mind to the his design style.   https://www.artstation.com/artwork/2xzkKe For $4 USA it was one of the better purchases I made this year.