A v-gouge, a sharpie, a compass, and a straightedge. There are certain advantages to having a brother who's a woodworker.
Engines are coming from the aforementioned Space Shuttle kits: Struts are thin card, plastic and brass tubing, and sheet plastic. Thanks to a timely purchase from Tamiya, I also have fuel tanks, a crane, and what will soon be a passable mech bay from a 1/400 harbor set.