Thanks for the kind words everybody
Grimnar
I can't say where I saw the video, I was channel-hopping through YouTube and the guy was showing off a complicated circle-cutting jig that he had made for his Proxxon that was adjustable and at the end he said "But for a quick job I just do this" and he pushed an old-fashioned flat-head thumbtack through the sticky side of some masking tape and stuck it down on the work surfaces so that the point was up, he then dropped a chunk of foam on the point and spun it around, Bingo! perfect circle.
I use Titebond because it was the wood-glue my Grandad always used, stronger and stiffer than white PVA. I lightly sand most of my blueboard surfaces with 60grit sandpaper to give the surface some texture, this causes the glue to hold better and dry faster.