A layer of a liquid composition containing (A) a heat-activated polymerizing agent for 1,2-epoxides, (B) a light-sensitive compound having in the same molecule at least one 1,2-epoxide group of formula ##STR1## and at least one unsaturated ester group of formulaCH.sub.2 .dbd.C(R.sup.1)COO-- IIwhere R.sup.1 =H, Cl, Br, or C.sub.1 -C.sub.4 alkyl, a mixture of (C) a compound containing at least one 1,2-epoxide group of formula I together with (D) a compound containing at least one unsaturated ester group of formula II, or a mixture of (B) with (C) and/or (D), is heated to solidify the layer, and subsequently it is exposed to actinic radiation in a predetermined pattern and those parts of the layer that have not become photopolymerized are removed by treatment with a suitable solvent.An example of a suitable polymerizing agent (A) is the complex of boron trifluoride with monoethylamine. An example of a light-sensitive compound (B) is glycidyl methacrylate. The epoxide compound (C) may be the diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane, and the unsaturated ester (D) may be 1,4-bis(2-hydroxy-3-acryloyloxypropoxy)butane.