Hi, all
Many thanks for the replies – and for the links, Thor & Mike – I hadn't considered making something myself, but the information in the links has whetted my appetite, especially since I know the whereabouts of a 'spare' Peatol lathe that I can probably lay my hands on fairly cheaply 
Roy – it'll be mainly small, fairly fine-toothed gears – the sort of thing you'd probably find in small clocks, or inside , say, a modern printer or scanner -maybe up to 100 or 120 teeth
Once I've delved into the links I'll probably have lots more questions – so watch this space 
Regards
K