Capsule (10) for two or more components of a material which are to be mixed together, comprising a cartridge (11) comprising an outlet (12), a first component chamber (13) for containing a first component, and a second component chamber (14) for containing a second component, the two chambers (13, 14) opening into the outlet (12); and a piston (15) which at least with its front end sits in the cartridge (11), lies with its rear end outside the component chambers (13, 14) and, when it is pushed forwards, presses the two components out of their component chambers (13, 14).