A method for forming a component for a gas turbine engine may include forming a first portion of the component that includes a cast metal or metal alloy, forming a second portion of the component that includes presintered preform defining at least one support structure, positioning the second portion on the first portion to define an assembly such that the first portion and the second portion define at least one cooling channel therebetween, and heating the assembly to join the first portion and the second portion and form the component.