The present application relates to a three-dimensional object created by Fused Deposition Modeling (FDM) of a modeling material from polyaryletherketones (PAEK), polyphenylsulfides, polyamide-imide, polyethersulfon, polyetherimide, polysulfon, polyphenylsulfon, polycarbonates (PC), poly(acrylonitrile butadiene styrene) (ABS), polymethylmethacrylate (PMMA), polyethyleneterephtalate (PET), polystryrene (PS), acrylonitrilstyrene acrylate, polypropylene (PP), polylactic acid (PLA), polyvinylalcohol (PVA), polyethylene (PE), polyoxymethylene, polyurethane (PU), copolymers of polyvinylalcohol and butenediolvinylalcohol and mixtures thereof, optionally filled with inorganic or organic fillers, wherein the object has a porosity of less than 5 vol%, as determined according to the porosity test procedure Porosity test'. The objects are leak tight and show improved mechanical properties. A method of producing such an object is also presented.