ah scroll saw explains it quite well acctually and i suppose you could automate the turning of the work piece in a cnc kind of way.

as for the laminating the shop bought ones are definatly done this way as i have one here with an mdf base and ply top frame and pieces. but i do understand that you could just sink in to a 12mm piece of mdf and then cut the pieces out seperate, it will use more material which i personally am fine with, but you can tell by the way these are that the top frame and pieces were all cut in one go from the same piece as there is a cut joining all the pieces.. as said above though scroll saw explains it