Blank #comics covers are awesome for getting sketches. I put a list of most of the blank #comics covers that can be pre-ordered at your local #comics shop this month in a post for the September 2018 Previews here on Steemit. I also like the Comic Con Exclusive books that you sell that leave space for a sketch on the back cover. I would have posted a pic of one of your sketch covers you had done for me in the past, but I did not have any scanned in yet. Sorry.