Recently I have become more interested in the medieval period, and although they organised themselves in large groups they were less likely to be in rank and file or so uniformed as say a Roman legion.
This meant more individual basing and after using loads of old coins or washers it was getting more and more expensive the bigger my armies got. The one day on a Flea market I came across these;
They are, I am told, Plumbers tools used for cutting washers. They come in a range of sizes, from 8 mm to 50 mm. For basing bods I use the 20mm one and for nags the 35mm one. They cut all sorts of materials, either using a twisting action to cut soft stuff like insulating foam (the light green stuff in the next pic) or cork or a hammer for harder materials like my favourite source of bases, old Ikea place mats, not shown in the next pic. (and you don´t need an Allen key either :-) )
The Smaller "disc cutters" are also pretty usefull for quickly making a mass batch of shields from thin card or old margarine tubs.