A device and method are provided for storing substances separately, and for mixing the substances prior to use. The device defines at least one first chamber for receiving a first substance, and at least one second chamber for receiving a second substance. A first sealing portion is located between the first and second chambers and is movable between a closed position preventing fluid communication between the chambers, and an open position permitting fluid communication between the first and second chambers for mixing the substances. First and second penetrable and resealable portions in fluid communication with the first and second chamber(s), respectively, may be used for filling by penetrating them with an injection member and introduce the substances therethrough and into the respective chamber, and resealing the injection apertures and the substances within the respective chamber.