Abstract: A tool module comprises an elongate carrying plate, an axle located with respect to the carrying plate towards one end of the said plate and a tool blade rotatable around the axle to move from a stowed position to a use position. The said tool module is adapted to be fixed together with a plurality of other such modules in a variety of configurations by means of a fixing device or devices passing axially through the respective axles of the modules thereby to form a penknife or multitool.