Huh: that's NOTHING! I'm sure some of you out there will have a copy of the British AeroModeller Annual of 1977/78, which contains an article by A. Walshaw, describing and illustrating his construction of a working 1/5th. scale model of a nine-cylinder Gnome-Rhone monosoupape engine of WW1.
Walshaw couldn't just build, he could write - the article contains such gems as a certain operation proving "laborious to the point of despair", while of another (machining the cylinder fins), "apart from tedium, no real problems were encontered". For the pushrods operating the cylinders' single valves, he used veterinary hypodermic needleds "of frighteningly large bore".
I'm sorry I'm not in a position to scan and upload a copy of the article, but perhaps somebody else with access to the book might be able to. It's well worth a read.
John