Stereolithography using vinyl ether-epoxide polymers

In the process for forming a three-dimensional object from a liquid polymer precursor comprising repeatedly exposing the surface of a bath of said precursor to a beam of actinic light to solidify successive layers of said precursor to make a green structure followed by postcuring of said green structure the improvement comprising employing as said liquid polymer precursor the composition consisting essentially of

• (a) at least one multifunctional vinyl ether compound;
• (b) at least one multifunctional epoxy compound;
• (c) an effective amount of a cationic photoinitiator;
• said vinyl ether compounds and epoxy compounds both being curable by acids released by said photoinitiator and having proportions of (a), (b), and (c) selected to provide a polymeric structure having suitable green strength with minimal curl distortion when said composition is polymerized by an actinic light source selected from the group consisting of UV and visible light lasers, the proportions of said vinyl ether compounds and epoxides being defined by the formula M=F/E
• where
• M is the vinyl ether equivalent weight of the composition and between 150 and 800
• F is the total weight in grams of the composition, and
• E is the number of vinyl ether equivalents in the composition.