This is a prop of the Arc Gun from the movie District 9. Personally, it's one of my favorite science fiction weapons. I might try the other District 9 weapons in the future. If you have recommendations for other props to build, please comment.
Step 1: Materials
-Cardboard or MDF
-Hot Glue and Epoxy
-Straws or Small Diameter Tubing
-Paint (Black, white, and orange acrylic; silver enamel)
-1/2~3/4" PVC Pipe, Wooden Dowel, or Square Stock (about 1-1.5' long)
-Modeling Compound (Auto body filler, foam clay, etc.)
-Old Wires and Cables
-Assorted Objects for Details (Be creative!)
Step 2: Drawing...And More Drawing
Draw the design of the prop on graph paper, or model it in a CAD program. If you have a papercraft software that makes templates for you, then use it. Otherwise, draw each surface of the prop on graph paper, and glue them to the cardboard or MDF sheets. It is helpful to label them according to which part of the gun they are for. (Stock, handle, main body, etc.) Cut them out with a knife, heavy scissors, or shears.
Step 3: Cardboard Boxes
Begin hot gluing the edges of the cardboard parts together to create the boxes that make up each part of the gun. Glue pieces of popsicle sticks to the insides at different angles to act as support, to strengthen the piece. Put glue on the inside of an edge, if possible, to make it look more professional. Glue on the outside can be painted to look like a weld, though. ;)
Step 4: Weird Barrel
To make the center of the barrel assembly, begin with a PVC pipe, wooden dowel or square rod. If you don't have one, you can do what I did and glue popsicle sticks together to form one long, squarish piece. Leave a few inches on one end to attach to that part of the gun I didn't have a name for earlier. Cut drinking straws or some other form of tubing into 1.5 inch lengths , and glue them at an angle to the main barrel. Cover them with auto body filler or foam clay, and mold it to look like the barrel on the Arc Gun. Look at pictures on the internet for reference.
Step 5: Combining Small Cardboard Boxes Into a Cardboard Plasma Gun
Lay out all the parts according to the original schematic. Notice that some parts are missing, particularly, the fuel tanks, wires, and other little mechanical bits. Look at a picture of the prop from the movie. I used some aluminium soda cans of different sizes for the tanks, cut wires from an old cable, and made the other bits out of stuff I found in a junk drawer. Be creative. Attach all the subassemblies together using hot glue, with popsicle sticks to add extra support, especially between the main body and forward grip. If you want to add more detail and texture, cut polygonal shapes out of cardboard scraps and glue them to the prop.
Step 6: Pretty Colors!
I decided to paint the gun in (almost) the same pattern as the movie. I used black, white, and orange acrylic paint, mixing black and white to create gray. I used painters tape to make clean lines and made small stencils for the alien symbols. I used silver enamel paint for the mechanical details, and for distressing. (I'm not good at it; if anyone has tips then please comment.) You can use the faux metal scratches to cover up mistakes in your paintjob as well. Coat it in varnish or finish it as desired. Enjoy your new Arc Gun prop.