This is my experience in making a Batmobile Transformer Costume. Total material cost for this project was a little over $150. It took 2 months of planning and 1 month of construction to finish so make sure you are serious about a costume like this before you start.
Step 1: Pre-Design Phase
Fewer moving parts will make things much easier on you. Try to get a general idea of where your head will be, what position you will be in when you are transformed, where pieces might be attached, etc. You can never be too prepared.
Make sketches to help you visualize it. Be very creative but just don't go too overboard with the moving pieces.
Step 2: Design Phase
You can sketch out individual pieces by hand, but that could take a while. I used Google Sketch-Up. It is a program you can download, much like Google Earth. Sketch-Up is a 3D modeling program that can give you very accurate sizing information. Just search for the program in Google, if you need instructions on how to use it, Youtube is your friend.
What is nice about Sketch-Up is you can download models that other people have already designed. I found a model of the Batmobile Tumbler that was designed by Angel Moore. Just search for a model of whatever vehicle you want to be. You can explode the components of the model and move things around to get a very good idea about where things will go. You can even download a model of a man to attach your pieces too.
As you are moving your pieces around try to think of how you are gonna have pieces move. Will they use hinges, flaps, velcro, hooks, etc. Make things as simple and practical as possible.
Important Notes: Have a fairly accurate idea of how tall, long, and wide your body is when you are standing up and when you are down in your transformed position. You can scale your model up and down to fit you accordingly. Pay close attention to the scale of your model and make sure to check your dimensions constantly. You don't want a costume that is too large or too small. Also understand that the modeling program is just that, it is a model. Your costume will probably turn out a little different than you plan, so don't get too bogged down in making your model perfect.
Step 3: Design Phase (continued)
If you are using a board material for you costume then make your pieces into 2-dimension elements. Use the dimension tool in Sketch-Up to give yourself dimensions so you can keep things sized correctly.
For your 3D pieces, break them down into 2D components and you will just have to glue or attach them later.
For anything circular, like tires, decide if you want to make them out of board or some other material. Circles are very hard to make with flat board so choose wisely.
Step 4: Beginning Construction Phase
If you haven't thought about materials yet, now is definitely the time. Most of the costume will be made of your board material. You can choose cardboard, paperboard, or something similar. I chose Structural Sheathing. You can find it at Lowe's for around $10 per 8'x4' sheet. It is like cardboard, but much stronger. I also chose this so I would not have to fiberglass it later.
Lay your board out on a large firm flat surface like a tile floor. Use a ruler and T-square to draw out your pieces onto the board. Use scissors, shears, or a utility knife to cut your pieces out.
Keep your pieces labeled!!! There is nothing worse than cutting a shape out only to forget what it goes to.
Step 5: Building the Back Component
Make sure that any gaps that will be taking a lot of abuse are reinforced. You don't want your costume to fall apart on you. After the back piece was finished I added hinges for my moving parts. To secure it to my back I cut the straps off an old backpack and stapled them on.
For the front of the car, the windshield folded back on a hinge and the cockpit area folded down over my head. To achieve a glass effect I cut sheets of plexiglass and painted them black on one side. The painted side faced the inside of the costume and gave a nice tinted look.
To get the cockpit to fold down I used two door support hinges I got at Lowe's. They are found near the door hinges. They allowed the cockpit area to pivot and extend and retract. All hinges were bolted to the board.
Step 6: Building the Arm Pieces
The front wheels of my costume folded back onto the arm pieces. I used metal door hinges to get them to fold and velcro to hold it in place. To attach it to my arm I stapled elastic straps to the piece. When it was finished it resembled a medieval gauntlet.
One issue I ran into was with balance. The wheels made the piece want to rotate around my arm. You could try and counter balance this, but I just attached a strap that I could hold onto to hold the arm piece upright.
Step 7: Building the Tires
I used a heavy duty black cloths to wrape the wheel frames. My girlfriend Rachel was nice enough to help stitch the cloth together since my sewing tasks need some work.
The rear wheels also use hinges which are bolted to the spacers inside the wheels. To attach the wheels to my body I used and old seat-belt belt (remember when those were in fashion) and attached velcro loops to the belt. The loops wrapped around each wheel set and when they were folded up, velcro kept them together.
I originally glued the front wheels to the arm pieces but they kept falling off, so I screwed and nailed the wheels straight onto the arm piece.
Step 8: Finishing the Build
I added spoilers to the top of the car, made out of board and long bolts. I cut spokes out and added those to the front wheels. Since the rear wheels had very large holes, I cut out large circles and painted spokes onto them.
I added shoelaces act as pull cords for the bottom wheels and for my side panels.
Most everything was spray painted black. To make the body look more exciting I used some copper spray paint to mist it from far away. This gave the body a nice bronze metallic shimmer. A few detail pieces were painted with the copper as well.
I tried everything on to make sure it fit and adjusted where I needed. I wore tight black running pants and a long sleeve athletic shirt. For my head I wore a gray swim cap to cover my hair, and a black paintball mask to cover my face. I felt this gave a nice robot look.
Last step was to go out and enjoy it. This project was a lot of fun and I'm very happy with the results of it. I can't wait til next year to start my next costume masterpiece.