I just went to Google and searched for the characters we wanted. Printed out large images of their faces to use as templates. I used felt to cut out all the faces and glued them to the front of the costumes with a hot glue gun.
My youngest was Chewbacca Bird. I used one of his shirts to trace a template and basically just cut the neck and arms a little larger and then made a big exaggerated body. I used some super soft funky furry fabric I found at JoAnns. I glued some fabric around an old beanie hat (make sure you stretch the hat out on something when gluing or else you won't be able to put the hat on when the glue dries!) it basically looks like a big furry Hershey's Kiss.
My middle son wanted to be R2D2 Egg. This costume was the easiest to make. I just bought a small adult white sweatshirt, cut the sleeves off and cut a hole out of the back of the top below the neckline preserving the hem of the neckline so that it formed 2 strings that I then tied together to make the neck fit. Once I put it on him, I stuffed the body with some batting. I bought a white beanie hat and used felt to create the R2D2 pattern around it. I used to lids glued together and wrapped in tin foil to create whatever that thing sticking out is. That was it. He wore a long sleeved shirt and sweatpants underneath.
My oldest was Yoda Bird. I used fleece material to create the body. I used a t shirt to create a template like I did with Chewbacca. I made the neck and arms a little bigger and then a very exaggerated body! I made the front and back pieces separate and attached them at the shoulder and sides with Velcro. I just cut a piece of tan fleece to drape around as the robe and attached with hot glue. I cut the eyelids using the same fleece and made them a little larger that the template I was using so that I could scrunch them up and make them look realistic. I also cut small strips of the fleece to create the wrinkles in the forehead. I used this tutorial to create the hat. I used this free printable for the light saber. Just wrap around a paper towel roll and add some rolled up posterboard.
My husband and I joined in on the fun too. Just T-Shirts with fleece faces for us though, but still cute!