Here is an astromech I created using Duct tape and recycled Styrofoam. Tools needed are a straight edge (ruler), utility knife (for cutting), Duct tape (use the good stuff it comes in many colors). Course file and sand paper (smoothing the edges), some sort of plans to help get all the right pieces in place. This project is in NO WAY endorsed or licensed by Lucas films or who ever owns Star Wars now. My daughter choose the colors. Spray foam comes in handy to fill some areas especially when shaping the head dome.
Step 1: legs and body
Here is the legs and body. I just traced out the shapes of the legs and taped the body up with a PVC core for basic shape. The body was removed from the PVC and rings of Styrofoam inserted. I taped with the cheap stuff to hold the basic shape and work out taping issues.