Stick insects look exactly as their name suggests. Since these bugs are very long and skinny, you need to add some height by making the costume longer than your actual height to give yourself more insect-like proportions. Use a thick felt material to make the body of the costume since it will be sturdy enough to stand upright on its own.
Cut enough felt to wrap around your body and extend to a height of approximately 2 meters. Feel free to make the costume taller than 2 meters, but it shouldn't be shorter unless the costume is for a child.
Wrap the costume around your body and have someone draw a circle where your face is located. To make it easier to get in and out of the costume, the costume should fold together in front. Mark the position of your shoulders, and cut out armholes. Cut two side slits at the bottom of either side so you can walk.
Paint the exterior of the costume with fabric paint to give it a more natural stick-like appearance. Brush on various shades of brown and green. Once the paint has dried, attach hook and loop fasteners to the edges so you can close the costume around your body.
Make four additional arms for the costume. The middle legs will be your own arms covered in brown felt, with the other four made of felt-covered coat hanger wire. Wearing safety gloves for protection, straighten out four coat hangers. Wrap felt around the coat hangers several times to give them a more padded look, then secure them with craft glue. After the glue dries, paint the legs the same way you did the body.
Sew the legs to the body above and below the armholes. Pull the coat hanger out a bit from one end of each leg, and bend it at a right angle to keep the felt covering from sliding off. Place the bent end against the side of the costume, and sew it with a matching thread. Bend each arm around the midpoint to create elbows.
Make two coverings for your arms out of felt, painting the same way as the body. You can close the sides by either sewing them shut or using hook and loop fasteners.
Use a piece of unbent cardboard to cut out a pair of antennae. Paint the antennae so they match the rest of the costume, then duct tape them to the inside of the costume at the very top. Paint two round black eyes at the very top of the costume.
Wear a dark brown long-sleeved shirt under the costume in case your costume sleeves start to slip.