Here's how I made my final school sports carnival costume: the Master Chief.
This costume was low-cost, (reasonably) low effort and time and low quality. I made it for the athletics carnival and all that was left in good condition by the end of the day was the helmet.
The cardboard cost me ~$40 but it could probably be acquired cheaper, or white cardboard could be used and painted.
The costume is made primarily of folded cardboard and hot glue. The undersuit is a wetsuit and the visor uses laminated cellophane.
Apologies for the sideways photos, the computer kept the rotation EXIF data but instructables didn't.
Step 1: Pepakura
There are 2 programs, Pepakura Viewer and Pepakura Designer. Pepakura viewer is used to view pep files and Designer is used to edit them. Chances are you'll need to edit them so download Pepakura Designer (Windows only, and I had trouble using it with the Mac version of WINE.)
The demo version of Designer has the limitation that it can't save changes, so you'll have to set it up and print straight away. In my case i installed PDFCreator, a virtual PDF printer, since my virtual machine couldn't connect directly to a printer, and I needed to create a file which could be shared to the Mac for print.
You'll also need the Halo Pepakura files.
This page has a database of them. I used ROBOGENESIS' Mark VI parts with a different helmet. ROBOGENESIS' ones have the advantage that they are easier to scale.
Step 2: Printing
Next, set the paper size you need in Settings -> Print and Paper Settings. Here in Australia, A4 is the standard, but the files are (depending on which ones you download) in US letter.
Now you need to set the scale. You can change the scale under 2D Menu -> Change Scale -> Scale Factor...
If you are using ROBOGENESIS' files, enter your height (plus a little bit) in inches into the scale box. I read to add a few inches for padding, but I added ~2.5 inches and most parts were a bit too big. You may be better off printing out a photo of yourself and of the chief and scaling accordingly.
A few things to note:
In Settings -> Other settings... -> Others
there is an option to set the font size of the numbers. Do yourself a favour and make this big.
Also in Print and Paper Settings select Print Lines clearly (vector print).
The Check Corresponding Face button (Ctrl-K) can be handy for figuring out what pieces go where later on.
In my case, every piece was a bit too big except the undies which were probably just right. This was once they were on, some pieces, like the chest, were still quite tight to get on but loose once being worn.
Make sure to check out
Step 3: Cutting
In addition to cutting through the hard lines, I found it necessary to lightly score the dotted lines in order for them to fold neatly. You may wish to score sections that are rounder less than the sharp edges.
Step 4: Folding
I'm not sure, but I think Pepakura attempts to unwrap it such that the numbers are on the outside, making it easier to find what goes where. Since this project requires them on the inside the entire suit is actualy inside out. The suit is symmetrical so this doesn't really matter, you just need to swap the right/left legs, arms, etc.
Step 5: Gluing
A bit of duct tape, masking tape and sticky tape was used on the inside in some bits.
Also, it may be best not to start with the helmet. I did, because it was the most important piece and I wanted to at least be able to wear it. Unfortunately my glue inexperience meant that it turned out fairly messy.
Step 6: Shoes
I found a pair of dying sandals and loosened the straps. I put the shoes into the sandals and glued the straps shut. This also gave them a bit more beefiness, keeping the pepakura shoes on tighter. The big trick was in the laces. you need to slip the whole thing on, lift up the pepakura to tie up the lace and then put it back down, which is quite difficult with the calves on.
Step 7: Gloves
I attempted to hot glue the handplate to the glove at a few locations and it held up pretty well.
Step 8: Undersuit
One thing the undersuit didn't cover was my neck, so I cut a strip of fabric from some black pants and put a two velcro strips on it. This worked fairly well, but the material and at times the velcro made my neck really itchy and scratched it a bit.
Also, the helmet flopped around a bit so I put some beanies on the fatten up my head a bit (I have a very small head).
Step 9: Visor
To make the visor I printed of the actual pepakura visor onto paper to get a size approximation. I cut the cellophane into three pieces so that it would fit into the laminator sheet and laminated them together. Using the pepakura sheet and the hole in the helmet, I cut the plastic into approximately the right shape and glued it in.
On the day the visor functioned surprisingly well, there wasn't too much of an issue with fogging and there were only a couple of spots where the cellophane sheets separated inside to create a blurry patch. Also, since it wasn't perfectly round, there were some "wobble lines" where things shifted as I turned my head, leading to some dizziness if I looked at the ground while walking.
Step 10: Attachment
For the calves and shoulders I stuck loops of elastic to the inside to hold them on (this didn't work great but it was ok).
The undies and thighs both use velcro (at the hips and knees) so that they can be placed on and then secured (sorry, no pictures).
I actually jammed the big wrist of the glove into the end of the forearm to keep them together and put them on as one unit. This meant I didn't need to worry about elastic in the forearm.
Step 11: Wear!
After putting on the wetsuit (which was the hardest part for me) and the neckpiece, beanies, etc. you can put on the armour.
First slide the calves on, you may need to put your hands inside to ensure the elastic comes up right. Put the shoes on and then put the undies on (they should be easy).
The Chestplate is the hardest part to get on, the best way I sound to minimise rippage is to reach both your arms up as high as possible and make your shoulders very thin, then get someone to slide it down over your arms and head.
Next put the shoulders on and then the forearm units and then the thighs.
Lastly, put on the helmet!
As you can see from some of the pictures, running around on wet grass destroyed the bottoms of the shoes pretty fast and I also had problems with the shoulders and thighs slipping down. Duct tape can fix this.
Overall I thought the costume went well, it stayed mostly intact for the day and I didn't get too hot or anything.