Thank you for this idea and link. There would be problems of cost and accommodation with such a device, and in keeping it busy in future. Maybe, though, I know somebody who has one. It is regularly employed cutting signage vinyls for a living, so it would not be polite to compromise its cutters with thickish hard sheet. If it could cut off the little corners of each pot then that would be pleasant. Also the half-millimetre slot for the tied pots.
In the meantime I could try cutting some strip, bevelling that, and the end corners of each plate prior to separating. Handling 4mm by 3mm pieces of plastic may or not be practical, and the placing of tiny chairs.
Another option would be run the yard in its 1930s form, before the pots came - they look new in the pictures taken in 1947.
Richard.