here is a nice little instructable for someone who has a little too much ambition, some time on their hands (sleep is for the weak) and a strong desire to have the best costume at the party

Step 1: Tools

gather these tools to begin your quest

riveter and rivets
drill and bit that can cut metal
duct tape (lots)
rubber cement
sewing pins
non-hemophilia (my amateur metal working puts the emphasis on 'amateur' and the metal is sharp
tin snips
scissors

Step 2: Construction Materials

here are the actual items you will need for this baby

2x garbage cans (regular metal ones from the hardware store)
high density foam rubber (jo-ann fabric or similar store)
a lot more duct tape
nylon webbing ratcheting come-along (also in hardware store)
backpack with waist belt
complete lack of shame
2x speakers
speaker wire
sonic impact t-amp
appropriate fabric for fur
ipod
a pair of children's eyes (or ping pong balls if you don't have access to children)

Step 3: Can Disassembly

with the tin snips, cut the bottoms out of the two garbage cans and split them down one side. one garbage can is not large enough to fit inside, so i put two together.

cut the lid of the two cans into triangular pieces. since you are going to have a larger diameter can, the original size lid will not fit.

please please please...after you cut the can, cover the edges with duct tape. they are very very sharp and i spent most of my halloween with bandages on my fingers.

Step 4: Fitting the Can Around Your Can

this involved a little customization. i am a tall guy, so i needed to make sure the diameter was large enough to fit inside. i picked a diameter that fit around my with lots of clearance. then i cut a piece from the second can to fit the necessary increase in diameter.

use the drill and your rivets. drill correct size holes through overlapping pieces of can and then rivet them together. cover the rivets with duct tape so kids and or drunks dont cut themselves.

i used the additional pieces from the second can to extend the 'skirt' of the can down lower, cause the can isnt all that tall.

i didnt grab too many pictures of this, but check out this one. you can see the seam across the middle of the can? that is where the first can ended and i extended the skirt.

Step 5: Test Your Can

no need to explain

Step 6: Rigging the Harness (yes, I Said Harness)

here is where you make the beast easy to carry

get your ratcheting come along. the way these work is that by operating the ratchet, slack is taken up in the line and shortens the length of the webbing. take the come along and put it together, creating a closed loop.

these will go in the can and act like shoulder straps.
cut two slits in the front of the can around where your pants pockets would be. feed a bit of the webbing through these slits and then tie the bit in a knot. this will keep it attached to the front of the can.

make a sturdy loop at the back top of the can. run the webbing through here to complete the straps. now grab your backpack and tape the webbing to its shoulder straps. this will allow you to have the weight of the pack resting on your shoulders and hips.

Step 7: Speaker System

mount your speakers on the inside of the can. initially, i put brackets in the can and taped them down, but they werent loud enough. i then cut sections out of the can that were speaker sized and held them in place with copious amounts of duct tape.

i got the idea for the sounds system from the great bike stereo instructableby gate. i hooked up the amp to my ipod and bought sesame streets platinum hits.

Step 8: Making the Head

rubber cement a couple of pieces (that are bigger than your head) of foam together. let it dry, then cut it down to a size that would fit over your head.

now cut out the middle so you can fit your head inside. also cut out a section of the front for the mouth. i also cut out ear holes and the back of the head to help with hearing and keeping cool.

test it your foam helmet.

cut two sections of black cardboard or black grid material to make the inside of the mouth. make sure there is enough space between them to see out of (and drink through if you are so inclined)

when you have perfected the shape and size and configuration of the helmet, then cover it with your fabric. trim the fabric to size, then attach it by putting lots of sewing pins through the fabric into the foam (this is easier than glue cause modifications are simpler) don't worry, the foam is plenty thick that the pins won't get near your head.

cut a mouth hole in the fabric.

attach whatever piece of brown fur you want for your eyebrow with hot glue. then take your ping pong balls, give them eyes with a marker and glue them down as well

Step 9: Make the Hands

measure some of the left over head material to make gloves. i just used a long sleeve shirt as a template, then held it toget with safety pins. i pinned a pair of running gloves to the ends and put my hands in the running gloves to have them stay attached ot me.

Step 10: Getting In

put on the gloves first

then lay the can on its side (it should be pretty sturdy)

reach in and put your arms through the backpack straps. pull it up and strap in. grab the head and go.