Id start at
www.tapplastics.com, great selection of acryic to make a res out of, as well as the solvents to bond it togeather. I actually made a res today with that stuff that I havnt posted on yet, maybe ill get working on that finally.
As for a radiator youll be hard pressed to build one. I started on a project using a section from a brass car rad thinking I could build and braze on some tanks. Never did attempt to finish it though.