So this was the first year in which my son really cared enough to have any input into his Halloween costume. We discussed and discussed and finally decided on Lego Spider-Man.

I'm by no means an expert costume maker. This is also my first Instructable, so bear with me. I'm pretty happy with the end result, which came together with a little Internet research, and a LOT of trial and error. Hopefully this can help the next person who decides to help their kid be a Lego minifigure for Halloween. This could be customized to be pretty much any Minifigure, really.

I'm organizing this in the order we built the costume: torso - head - legs - finishing/fitting. It actually turned out to be a really good order to do it in for management of resources.

This took about 4 pretty full weekends to do, but I'm an amateur. Someone with more costume experience could work much faster.

Please let me know if there's more you want to see/know. Like I said, this is my first Instructable, so I may have missed something. I'm happy to edit what I can to clarify!

So, here we go!

Step 1: Materials

I'm not giving exact amounts of materials here, as fit/size will determine much of that for you. I didn't buy anything crazy, so everything I used should be readily available to most people.

Torso:

Foam core boards
Glossy Contact paper in red & black (purchased from a sign shop)
Rust-o-leum glossy deep blue spray paint
Poster board (blue, but the color doesn't really matter here)
1/4 round moulding
Blue duct tape

Head & Hands:

1-1/2" foam insulation sheet
Red poster board
Glossy contact paper in red & black (purchased from a sign shop)
Foam safe adhesive
White pantyhose
Krypton short cuts "red pepper" spray paint

Legs:

Cardboard boxes
Rust-o-leum deep blue gloss spray paint
Blue duct tape
Poster board (any color will do)
Gorilla tape
Gorilla super glue

General:
X-acto knives (regular and long)
Gorilla super glue
Foam-safe adhesive
Gorilla tape
Sandpaper (very rough and very fine)
Patience

Step 2: Torso

The most important thing to do for each of these parts, torso included, is to make a mock up to check for size. The most obvious mistake in the costume will be a mistake in scale.

I took an image of Lego Spider-Man and used it to scale against measurements of my son. I used those measurements to create the pieces of the torso in poster board, to check the sizing.

After getting approximate measurements, I used them to cut the pieces out of poster board. This is a little easier to work with than the foam core, and a lot less expensive to make mistakes on. I built a wearable mock-up of the torso out of poster board and scotch tape, which my son tried on.

When we had everything the right size, we took apart the mock-up and used the pieces to trace directly onto the foam-core, before cutting it out with an xacto. In The pictures, you can see tabs on the poster board. These were only used on that part. There are no tabs on the foam core.

When the pieces of foam core were cut out, we had to score the bottoms with the xacto (on the front) which allowed us to bend the flat part on the bottom giving the torso the correct shape.

All foam core pieces were spray painted blue before cutting. Be careful painting the foam core, as the edges have exposed foam, and the paint will eat that foam, mangling the edges. You don't need the edges painted anyway, as you will cover them with blue duct tape later on let the paint dry for 24 hours before cutting or using the contact paper.

We then cut the red sections for the torso out of contact paper. I drew these freehand on a large piece of paper, then used the paper as a stencil to cut out the contact paper. The contact paper is a big sticker, so it is important to be careful when sticking it to the torso to avoid wrinkles and bubbles. It can be pulled up if you make a mistake, but if you do that too many times it will stretch and look wonky, so it is still important to be careful.

After applying the red contact paper, we made the spider from black contact paper and an enlarged picture from the Internet. We applied the spider and then moved on to the webs. The webs are made from thin strips cut from the contact paper. If applied carefully, you can curve the strips to make the inner sections of the webbing.

When all the pieces were cut out, we attached the front to the two sides. The 1/4 round moulding is used in the corners to give it stability. Glue is applied to the edges of the moulding, and it is pressed into the corners.

After the glue dries, take a piece of blue duct tape and split it down the middle with an xacto. Those pieces will be carefully placed over the edges to give the torso a more finished look.

The back will be attached with Velcro so that the wearer can get in and out.

Step 3: Head & Hands

The head was definitely the trickiest part of this whole project. I really wanted the scale to be right, so we measured carefully and still had to do some trial and error.

The top and bottom of the head are polystyrene insulation (1.5"). It would have been a lot easier to work with this if I had a hot knife, but I didn't, so I used the xacto with an extendable blade. Once we had 4 circles (top, bottom, top knob, bottom knob) they were sanded down to give the edges the curve that they needed, and to make the top and bottom parts the same diameter.

We then cut a piece of red poster board to put around it. Unfortunately, it didn't go all the way around, so we cut an additional piece to bridge the gap. Since we wanted the seams to be hidden, we measured it so that the contact paper for the spider web on the back would cover it up. That worked better than I could have hoped. You can't tell at all!

Before gluing the poster board on to the foam, we cut out the eyes. SAVE THE PIECES YOU CUT OUT. After cutting them out, we took the white pantyhose, and stretched them as far as we could over the eyes on the inside of the poster board, then glued them down.

After the glue dried, we covered the eyes with the pieces we saved and some masking tape, and then glued the poster board to the foam top and bottom. Covering the eyes protects them in the next step... Spray painting.

To make sure that the head was a uniform red, we sprayed the whole thing with Krylon short cuts. Regular spray paint won't work, as it will eat the foam. It is also important to do a lot of thin layers, as you want the paint to look good. The head will be a focal point of the costume.

When the paint dried, we removed the eye covers. There was some unpainted area around the eyes, but this would be covered by the black contact paper going around his eyes. This was cut out freehand and applied.

We then used careful measurements to make sure the webs were in the right spots on the front and back. This required a lot of time and patience to get right. Overall, though, I'm quite pleased with how it turned out.

The hands were created in much the same way as the head. Three rings were cut out of the polystyrene and glued together and sanded. Proportionally, it was almost perfect. We then spray painted them, but weren't happy with how they looked, so we ended up covering them in red contact paper. You can see the uncovered hand next to a covered one in one of the pictures.

We then attached a toilet paper roll (filled with foam) to each hand and covered that in contact paper. This is how he will hold the hands.

Step 4: Legs

The legs proved trickier than I expected, but still doable at the end of the day.

Again, it was important to use poster board to create templates. I created a leg template that we tried on my son. When we had the appropriate sizing, we took it to the cardboard.

The legs are made from regular corrugated cardboard rather than foam core. Actually, I found USPS board game boxes were the best size here. The reason for this is the need to make the curve in the leg, which is relatively easy with the corrugated cardboard, but seems hard if not impossible with foam core. The cardboard is also more durable which will matter as his legs will be kicking against the costume here.

The most important thing to figure out is the cutout for the crotch. This can really only be done with trial and error. My son may need to wear heavy pants under the costume (it can be cold on Halloween in Minnesota) so I wanted to leave enough room to allow for that.

It is also important that there is clearance from the ground. I tried to get the bottom of the feet to be about 3/4" off the ground. They ended up a little higher than that, which I'm not thrilled about, but at least he can walk.

Inside the legs were initially held together with gorilla tape, and then we glued moldings to the straight edges inside to give it more strength. The outside has blue duct tape on the edges for finish and for durability.

Each leg is one whole piece, and he will have to be lifted into the from the top. It's easy enough to do.

Step 5: Finishing/Fitting

To make everything wearable took nylon webbing and a lot of Velcro. We attached the webbing to the legs making straps that went up over my son's shoulders. It is important to keep the bottoms of the feet about an inch off the ground, or he won't be able to walk. We also ran a strip of webbing across the back and a piece of Velcro across the front to keep the straps from slipping off his shoulders.

We stuffed his arms with the cut pipe insulation (2"), which I think improves the look of the arms. They're not perfect but for mobility for trick or treating we ended up making a few sacrifices.

Then we attached the back of the torso to the front with six strips of Velcro. I added a little extra moulding on the inside to make sure the body maintained the correct shape. I leave one side's Velcro attached all the time and just remove the others to let him in and out.

Overall I'm very happy with how it came together. Getting the right proportions was really important to me. I feel we really managed to pull that off.