A compartmented pouch has two or more sealed compartments formed therein, these compartments being separated from each other by a breakaway partition. One of the compartments has a stencil formed therein which may be in the form of holes punched in one wall of the compartment arranged to form a desired marking image, which may be letters, numerals or symbols. In lieu of punched holes, the images may be formed by slots in this compartment wall. Removable tape is placed over the holes or slots. One of two fluid components is placed in one compartment and another of two fluid components is placed in another compartment which may or may or not be the compartment having the images formed therein; these two components forming an etchant or marking material when combined together. Pressure is exerted on one of the compartments to force the fluid therein against the breakaway septum or partition causing the partition to break, such that the fluid passes into the second compartment to mix with the other fluid, thereby forming the etchant or marking medium. The tape covering the holes or slotted portions forming the marking image is removed and the stencil is placed against the surface to be marked, the etchant or marking medium being permitted to pass through the holes or slots in the stencil and onto the surface to be marked. In another embodiment, a single fluid may be employed, which is contained in one of the compartments.