Step 1: Materials!
-2" and 8" round containers/bowls (for eyes, mouth and hole for head)
-12" Cement form tube (found near construction materials)
-3/4" Styrofoam Insulation (found near fiberglass insulation) *
-2-3 cans of Yellow spray paint * (Krylon's Sun Yellow is a very close match to LEGO yellow)
-2-3 cans of red/blue/green/other spray paint (color of body, your choice)
-Sandpaper (400ish grit)
-A sheet of copy paper
-Spray glue (preferred over hot glue because of styrofoam)
-Speaker fabric or black panty hose (So you see out of but others cannot see in)
-A strip of Velcro (the hook side)
-Yellow Kitchen gloves
-Long sleeve shirt (matching to body color)
*Here's the deal about spray paint and styrofoam. Spray paint cans contain an aerosol that loves styrofoam and dissolves it on contact. I will explain how I overcame this and improve the durability of the head in a later step.
Step 2: The Head!
First you will need to measure from the top of your head to your chin and round up to the nearest inch. My noggin is about 8.5", so I made it an even 9". This will give you how much you will cut from the form tube. Measure that length on the form tube and starting cutting with the handsaw carefully to get the straightest line possible, I used a rubber band to aid me. After its separated, sand the edge you just cut to smooth it down.
Next your going to cut some styrofoam, this can get very messy so have a vacuum/shop-vac on hand. Take the form tube you have cut off and draw the circle out on the styrofoam. Take two sheets of the styrofoam and cut the circle out slightly bigger to sand down later. Do this one more time to create both the top and bottom of the head. You'll have four 3/4" disks total to work with. Two disks for the top and two for the bottom.
The trickiest part of making the head is making the curved ends. Use the spray glue to combine two disks together. Your going to sand this curve into the styrofoam, so take your time and check your work to make sure the curve is even throughout the disk. This will take awhile and there may be easier ways to do this; there could be a part or product somewhere that fits the form tube and provides the curve needed. I just worked with what I had and it turned out great.
Once the curves are similar to the mini-fig's curve, we need to attach the ends to the form tube. Remember when I told you how spray paint loves styrofoam? Well this is the step that you have been waiting for. We are going to tape over the ends.*See alternative methods below* The main reason is to provide that barrier so the styrofoam doesn't make like a magician and disappear. The tape also secures the foam and makes the head a much more durable. Decide which side you want to be the top and secure it by using one continuous strip of tape across the styrofoam, leaving about an inch on the form tube. Continue this until none of the styrofoam is exposed anymore.
Before we tape up the side your going to squeeze your head through, we're going to need a hole made. Take the 8" bowl you'll use for the face later and center it on the bottom piece of styrofoam then mark its position. Now cut the piece out until you have a styrofoam ring. Don't discard this disk, we'll use it in a bit. To tape the bottom is slightly different. Instead of taping across the gap, wrap it around so attaches to the inside of the head. Do this until none of the styrofoam is exposed.
The stub on the top on the head is made up of three 6" disks from the styrofoam. Lucky for you, the 8" disk you just cut out is already two pieces of foam. Cut the disk down to a 6" diameter, make another 6" disk from the foam and glue to the others and you have the stub. Sand the edges so they are smooth.
Now its time to ventilate your head before you attach the stub. Find the center on the top of your head and use the 2" cup to trace your vent hole. Cut through the tape with the X-acto knife and the styrofoam with the steak knife. Find the center of the stub and do the same. Tape up the stub until no styrofoam is showing, leaving the vent hole uncovered. Use 4 or 5 dabs of the Gorilla glue to attach the stub to the head, aligning the vent holes.
After a few suggestions, I figured it would be a good idea to include them into this instructable. Destructions presented a couple of ideas where you could use a higher density Styrofoam then use a lightweight spackel to fill the gaps for an even finish. Yoyocrazyguy mentioned paper mache, which would solve just about all the issues with Styrofoam as well as keeping things nice and smooth. Teethdoc used a product called DecoArt MagiKote which is made specifically for Styrofoam to harden it into a smooth, paintable surface.
In my opinion, the Magikote would work the best in this application. All you would have to do is brush on a couple of coats of it onto the Styrofoam areas to be painted, let dry overnight, then sand till smooth. One catch is that you would have to make sure the Stryofoam is secured from the inside of the head with either tape, gorilla glue, or a combination of the two.
Step 3: The Face!
This part is a little hard to explain so I have pictures to detail the processes as well. I have estimated the eyes are about 2" in diameter. So take that 2" round object and sketch it onto the copy paper. In the LEGO man diagram, the eyes are the same distance apart (end to end) as the stub on top of the head, about 6". Mark the distance but don't draw the other circle yet. Take the paper and fold it so the line you marked matches with the other eye and sketch the circle on this side. Unfold it and you should be able to see the mark you made on the other side, redraw that circle on the other side. This is to make sure the eyes are level with each other, we don't want to make a lazy eye LEGO man.
The smile is simple but difficult to recreate. The "peaks" of the smile is 2" from the bottom of each eye, mark each point. I found that a 8" round bowl creates the right radius of the smile. Align the bowl with each mark and connect the dots. Now mark two more points one more inch below each peak and connect the dots once again with the bowl. Rounding the ends of the smile was done by free hand, do your best to replicate the ends and use a pencil so you can perfect it before you begin the surgery. Mr. frob has suggested using a compass for the ends. A 1/2" radius circle will give you the right curve to connect the end points of the smile.
Step 4: Positioning the Face.
The bottom of the smile is located roughly 2.5" from the bottom, but the length of your head could alter the look, so do your best to center the face on the head. Now tape the copy paper to the face, making sure its level and prepare for surgery!
The way I took was use the X-acto knife to cut the eyes and smile out of the forming tube. This takes awhile and there may be other ways to do this if you have the right tools. Take your time, any mistake and you might have a LEGO man scar on your hands.Cut the face out slightly smaller than what is drawn, when you sand it later to smooth it out it will remove the extra cardboard.
Step 5: The Body!
Once you have the numbers down you can grab the boxes and start making the body. The LEGO mini-fig as a wider waist than its shoulders and looks much like a trapezoid. So when you cut the front and back of your body pieces, make sure you angle the sides similar to that of the LEGO mini-fig. The final dimensions of my LEGO body was 15" for the shoulders/top, 23" for the waist/bottom, 21" from top to bottom and 13" deep.
Now that all the body pieces are made, we can tape up the parts to make the whole. Once the body is taped together, we'll need to make holes for your head and arms. Cut the top big enough to fit your head trough comfortably. The arms holes need to be much larger than the arms themselves to allow full movement in the costume. Cut a 'U' shape on the sides to match up with the top piece of the body. Apply more tape when necessary.
Step 6: Painting!
Step 7: The Brains!
Get the hook side of the velcro and stick it around the holes of your face. This will provide the "glue" for the speaker mesh/fabric that you will look through. Cut the speaker mesh to fit over all the holes and push it against the velcro until it stays.
The foam is to secure your head inside the LEGO head. Cut the foam and place it in strategic spots so when you turn your head, the LEGO head stays in place. Use the Gorilla glue to apply foam where you need it and let the glue set over night and apply more where needed.
Step 8: Be one with the LEGO.
Of course this is not the end of your LEGO costume. There are hundreds of LEGO characters you can create. I plan to redesign my costume to look like a pirate for Gasparilla at some point. Perhaps you're going to a pimps and hoes party. Grab a cane, make a hat and paint a suit on your LEGO costume and stride in style. Have fun with it and be creative!