I spent a great deal of time at the Pixologic Zbrush booth this year as they were showing off the much anticipated ZBrush 4. Pixologic selected a handful of the world's best zbrush artist's to come down to LA to demo the software and I have to say, this was one of the coolest, most inspirational things I've sat through. Probably my favorite demo was by an artist named Jelmer Boskma who is primarily a character artist. You can see his work here: http://jelmerboskma.com/ . During his demo he showed off a technique for super quick concept drawing that he had picked up from someone else that basically involves mirror painting with a smooth brush. Now, I haven't done much drawing or digital painting for awhile so I'm still getting used to the technique but I have found it to be very useful. Here are a handful of rough 15 minute concepts I came up with.
I ended up taking the first image a bit further while modifying it to work better in 3D and sculpted this from zspheres in about 1.5 to 2 hours.
I have yet to render a turntable but will update with that as soon as I have one. I really intend to keep up with this sort of work as it doesn't take much time and is capable of producing pretty strong concepts.