A process of manufacturing a three-dimensional object includes a step of depositing and solidifying molten polyvinyl alcohol to form a support structure; and a step of depositing and solidifying a molten thermoplastic polymer on the support structure to form a three-dimensional preform. The support structure has a mixture of at least 50% by weight of polyvinyl alcohol and at most 50% by weight of at least one polymer of polyvinyl butyral, polylactid acid, ethylene-vinylalcohol-vinylacetate terpolymer, vinyl acetate-vinyl pyrrolidone copolymer, acrylonitrile-butadiene-styrene terpolymer, polycaprolactone, vinyl acetate-vinyl caprolactame copolymer, and polyvinyl alcohol having a degree of hydrolysis DH of 30-65%. The support structure can be dissolved to form the three-dimensional object.