A method of forming a three-dimensional object, which method includes a cleaning or washing step, is carried out by: (a) providing a carrier and a fill level, and optionally an optically transparent member having a build surface defining the fill level, the carrier and the fill level having a build region therebetween; (b) filling the build region with a polymerizable liquid, the polymerizable liquid comprising a mixture of (i) a light polymerizable liquid first component, and (ii) a second solidifiable component that is different from the first component; (c) irradiating the build region with light, to form a solid polymer scaffold from the first component and also advancing the carrier away from the build surface to form a three-dimensional intermediate having the same shape as, or a shape to be imparted to, the three-dimensional object and containing the second solidifiable component carried in the scaffold in unsolidified and/or uncured form; (d) washing the three-dimensional intermediate; and (e) concurrently with or subsequent to the irradiating step, and/or the washing step, solidifying and/or curing the second solidifiable component in the three-dimensional intermediate to form the three-dimensional object.