Firstly I have to give credit to another Instructable which gave me the idea to use a sweatshirt and socks for this costume. It's called No-sew octopus costume and it's awesome, go check it out!

My version involves a few differences so I thought I'd make an Instructable in case anyone wanted to make one like mine.

Step 1: Gather Materials

You will need:
One hooded sweatshirt
8 matching knee high socks
80 matching buttons (I used two different colors but you'll want them to be the same size)
2 larger buttons for eyes
One foam wreath circle.. mine was 12" which works for a small toddler.
Two half spheres of foam for eyes
Hot glue and glue gun
Stuffing of your preferred type to make the legs

Step 2: Make Legs!

Stuff each leg about 2/3 up, leaving enough room to fold the top over (this will make sense later).

Hot glue 10 buttons in two rows of five on the bottoms of the socks for the octopus suckers.

Step 3: Attach Legs

The foam wreath is meant to keep the octopus legs out away from the kid's actual legs, which makes them stand out but also makes it easier to walk.

Fold each sock over the wreath and hot glue the sock to itself (see photo), removing stuffing as needed. I tried to alternate the direction my socks were facing so that the legs looked more dynamic. It might look weird if they are all facing the same way!

Step 4: Make Eyes

I got glued small buttons onto the foam half spheres to make eyes, but they came out looking like frog eyes haha. Real octopus eyes are pretty weird. I think using larger buttons would make them better but I didn't have any. I'm excited to see the eyes you all come up with!

Hot glue the foam pieces to either side of the sweatshirt hood.

Step 5: Attach Legs to Body

I decided to leave the pieces separate and put the sweatshirt on the kid first, then the legs. She was afraid to put the whole thing on at once. However, I did cut slits in the ribbing of the sweatshirt on either side to make the foam fit more easily. You just slide the foam circle up around the kid and then pull the sweatshirt down over the foam.

Done! Go trick or treating!!