Multiple Masks Per Product - Or circular image Zone Clipping

I am trying to create a template for a sheet of 12 round discs per A4 page.  Each of the discs will need to have the ability to be a different image (or all the same if the user wants).  I can't seem to figure out how to create a circular 'image zone' and note there is only the ability to have one .svg mask per product design.  

Any help on how to do this would be fabulous.