A method for preparing a microporous ink-impregnated marking structure according to the invention involves use of a window-like frame instead of a conventional chase. The frame is placed on the upper face of the matrix board or mold so that the premix, containing ink, plasticizer and resin, is retained therein. The premix fills the cavities and excess premix forms a continuous layer over the cavities in the mold, with the edges of the layer retained by the frame. A layer of an ink-absorbent backing material is placed on the layer of premix, and the backing is covered with a plate. The assembly is heated with pressure to form a microporous, marking fluid impregnated structure having a relief pattern corresponding to the cavities, and then cooled. The marking structure can then be used to make self-inking hand stamps.