The circle cutter is basically a long arm which fits into the side of a craft knife,you swing the arm several times to get a really slick cut in card,balsa etc. They also do a circular cutter which fits into a custom handle,it looks a bit like one of those pizza wheel cutters you get in Tesco ! this tool is great for cutting solarfilm or any heat shrink covering material,for the lightweight modeller who uses tissue you can cut through several layers at a time. Finally the etching tool is a barbed blade which drags a very clever line removing material at the same time,ideal for use with plastics or acrylic sheet. Keep an eye open for these tools in your local shops,they come in yellow plastic with metal screw fittings that are knurled. The above three are the ones that I know about but there must be others around from this company.