For this years science fiction convention I decided to go as a cyberman from Dr. Who. specifically, the cyber controller from the episode Earthshock. It took about 2 weeks to build the costume and about two days to make the gun.once it's done it is reasonably light and easy to move around in.
To make it you need

Card board
Silver tape (the kind that you use on air vents and the like).
A plastic bottle, 3.5 inches in diameter
Red and black tape, or paint it isn't used that much
A silver jumpsuit and gloves (or if you can't find that buy some coveralls and spray paint them silver like I did)

Step 1: Helmet

I made this a while ago and it is what inspired me to make the complete costume. The Instructable is right Here.

Step 2: Chestpiece

To make the top of the chest plate you cut out two pieces of cardboard with the specifications of the picture below (I felt that it would be easier to show a schematic than try to explain it with words alone). You may have to alter the measurements slightly depending on your size so measure yourself to make sure that it will fit. Once that's done fold the two pieces into an ark so that they lay flush to each other and tape them together. then cover the entire thing in silver tape and make sure that the hexagon is a clear indentation. Next, take a piece of cardboard that's four inches square and coat in in black duct tape, then glue it to the center of the hexagon. this concludes the top of the chest piece.

Step 3: Chestpiece II

The next step is to add the piping around the midsection, for this you will need three cardboard tubes each six inches long and with a one inch diameter. The first two are plain, with no special adornments so they just need to be colored silver with tape and put to the side. The middle one is a bit more complex and it needs to have multiple ridges created by eight bands of cardboard rapped around the exterior of the tube. The top and bottom ones are twenty cm thick while the middle six are about five cm thick. Glue the top and bottom ones on first, then attach the small ones at equal lengths in the remaining space. With this done, apply tape to it to make it silver and attach it to the bottom of the chest piece.
For the bottom of this piece cut out two trapezoids.

7 x 6 x 3 x 6 inches
2 x 5 x 6 x 5 inches

Now to make the sides cut out 4 smaller trapezoids

6 x 1 x 7 x 1inches
5 x 1 x 6 x 1 inches
5 x 1 x 6 x 1 inches
2 x 1 x 3 x 1 inches

Now tape then all together to form a closed three dimensional shape and attach it to the bottom of the piping so that the smaller trapezoid is facing out.

Step 4: The Feet

The feet were relatively simple. Take a pair of sneakers, ones that you wear a lot and coat them in tinfoil so that the tops are completely covered but there is only a narrow lip on the bottom of the shoe, this makes it easier to take the shoe cover on and off. now add two layers of silver tape to the tinfoil and make sure to rap it around the lip on the bottom (this is to keep the shoe cover in one piece, if you try to walk with only the tinfoil it will be quickly torn apart). To make the covers removable cut the heel open then add additional inch of tape to one side of the cut and attach some velcro strips to this area to make the cover easy to put on and take off.

Step 5: Jumpsuit and Gloves

This will form a large part of your costume and there're two ways to go about it...

you could buy a silver jumpsuit and gloves online, but finding a good one would be hard, I know I tried.
you can buy a cheap pair of coveralls and gloves and spray paint them silver. This is easier and probably cheaper but unless you buy a quality spray paint it may start to flake of the suit after a little while.

Either way, this is a large portion opt the costume so make sure you are happy with it!

Step 6: The Gun

The creation of the gun is divided into three parts,

the barrel
the body
the handle

♦ the barrel
The most important part of the barrel is the clear tube in the middle aka the plastic bottle, it should be three inches in diameter and about eight inches from top to bottom. first, cut off the bottom of the bottle so that you can insert the core later, then take a piece of cardboard four inches thick and wrap it around the top of the bottle where it begins to taper into the bottle neck and paint it black. then make a, for lack of a better term, silver ladder to form the top of the barrel. To make this put two pieces of cardboard about half an inch thick three inches away from each other and parallel to each other, then put three inch long strips of cardboard, about 1/4th of an inch thick each, and in between the two parallel strips and tape them together with silver foil tape. now wrap this around the top of the barrel and glue it down. Finally, paint of tape black stripes on the barrel and get to work on the body.

Step 7: The Gun II

♦ The body
Cut 2 regular hexagons out of cardboard with the length of each side being two inches, now cut six rectangles out of cardboard that are 2 by 7.5 inches and tape these to the two hexagons to make a hexagonal prism. put string along each seam of the prism and tape it down to form ridges. now cover the entire thing with the foil tape. now make a smaller hexagon, only one inch per side, and tape it to six smaller rectangles, 1 inch b 1/4 of an inch and tape them to the sides to make a smaller hexagonal prism that is open on one end. Glue this to one end of the main body, and glue a five inch long paper towel tube to the back of this and secure all of it with silver tape. Finally, cut a rectangle that is six and a half inches long out of cardboard and role it into a tube with a circumference of two and a half inches. wrap some kind of red foil (for example reflective red wrapping paper) around the tube and glue it in place, then glue the tube to the end of the body that doesn't have the narrow tube already on it. The red tube will go inside the plastic bottle to make it look like the core of the gun, so set it up so the core is in the bottle and glue/tape the barrel to the body. add black stripes on every other side of the body (the bottom and the two on either side of the top) and this part is done!

Step 8: The Gun III

♦ The handle
This is a fairly simple step, there is a pattern for the handle beneath this, copy it onto cardboard five times over, cut them out, and lay them on top of each other and tape them together with the silver foil tape. Then, crazy glue them to the body of the gun and tape over that to give it extra support. add the four black stripes to the handle and you are done the gun.

♦ The strap
The strap was for an old computer bag that I had laying around, I attached it by wrapping a bit of silver tape around some string and taping that to the body and the handle enough times so that I was sure it wouldn't break. Then I clipped the step to the loops and it was a done deal.

That's it, you are now a Cyberman. So go, kill the doctor, conquer the universe and delete!