Cutters with snap-off blades are not only indispensable tools in the realm of model making because their ever renewed and sharp blades can also make clean cuts through all sorts of other materials.
The larger cutters (for 18 mm blades) are best used for cutting thicker cardboards, plastic foils and films, thinner wood slats and mouldings, thin metal sheets or carpets. Cutters with 9 mm blades are usually used for cutting paper, cardboard or thin plastic foils or films.
You can only cut exact corners in a flat material if you make separate cuts for each leg of the corner (that means, for every rectangle, 8 separate cuts must be made). In order to make straight cuts, care must be taken that the cutter remains at the same angle during the entire path of the cut. The cut edges will be all the more smooth in direct proportion to how flat the blade is as it passes through the material. It is particularly important to have the blade as flat as possible when cutting KAPA or rigid foam sheets, because these types of material will crumble fairly easily. It is in such cases that cutters with snap-off blades really display their worth because for these kind of cuts the blades can be pulled out of the handle to the appropriate length.