Baren!

Well - apparently that is what it is called. 
Used by artist printers to burnish (i.e. press) the paper onto e.g. a cut and inked lino.

around 70mm across, made of glass and hand decorated.

They are made from many and varied materials, including one where the handle is moulded plastic and the surface bearing down onto the paper is multiple ball bearings.

I am a day behind with blipping - probably catch up tomorrow as I have a birthday blip to assemble!