I don't know about you, but I sure think it would be AWESOME to have an Instructables robot figurine. Actually, I bet you think it would be awesome too.
So here's how to make one. :D

Step 1: Materials

You can get most of these things at Walmart for pretty cheap.

Things you'll need for sure

Green foam florists use. ($1.48 for 3 pieces that are 3.5" by 3.5" by 3") This stuff is fun to cut up and is very easy to carve things out of. Don't use styrofoam, it isn't as easily carved. Be sure that it's thick enough to carve a 3D thing out of it
Plaster of Paris ($3.97 for 4 pounds at some hardware store)
A picture of the Instructables robot. Make sure it's not too big.
An X-acto knife. This is what I mostly used to carve the foam with.
A plastic cup and fork for mixing the Plaster of Paris. You might want to have some water for it too.
A few paint brushes. Make sure at least one of them is one you don't care about at all because it will probably get ruined.
Paint. You'll need some yellow and a little bit of red and gray. You might want to make his arms legs and head a bit more orange-ish

Things that will help a lot.

A steak knife
Maybe a pair of scissors to cut out the picture of the robot
A metal barrette like the one in my picture. It helps for cutting the foam out from between the robots legs.
Sandpaper
Newspaper! Clean-up will be SO much easier. But it's really hard not to get green foam pieces everywhere even with newspaper. Especially if you're outside and it's windy...
Pins

Step 2:

For this you're going to want to put the picture (already cut out) on the biggest face of your block of foam. If you can't/don't feel like holding it onto it put a couple of pins into it to hold the paper on. Trace around the robot with and X-acto knife or something, but cut as far into the foam as you can (I would recommend an X-acto knife for this instead of a steak knife or something).

Step 3: Tell the Dog to Get Away Because He's Getting Foam All Over Him

Now cut off the bigger chunks you aren't going to use for this, which is pretty much everything outside of the outline of the robot. But be sure to keep the shape of the robot all the way down the block!

Once you have the bigger chunks off you'll have to cut off some of the smaller pieces. Sometimes it can be kinda hard to make sure you cut it straight all the way down. But don't worry, as long as it's pretty much robot shaped all the way through you'll be fine.

Step 4:

Making the robot so that it has 3D features is not as hard as it might seem. I spent a lot of time during health class thinking of how I would give him 3D features though :P

Anyway, the first thing we'll make on him is a head.

I'm sure you can see where his head is supposed to be on your foam robot. Unless you messed up and created a mutant robot. So stand him up and look at the top of him. You'll want the middle of the block of foam to be somewhat centered between the two cuts you will make on either side of it. Make the cuts far enough away though that his head is a cube. Only cut through the top down to where his neck would be though, don't cut all the way through the block to his feet. That would be bad. He would only partially be able to be 3D!

Then put it on one end (the base, if we were considering this to be a prism) and cut at his neck down to where the cut you made from the top is. Then flip it over and do it to the other side. I think the pictures will help if this is kind of confusing.

So now there should be a cube sticking out of the top of it and it will kinda look like a little house with a chimney in the middle of the roof.

Step 5: The Arms

The arms are going to be made the same way as the head was.

His arms will be about lined up with the middle of his head, if you can actually cut well, unlike me...

So make two cuts to form a piece that will be an arm. Then just cut off the rest of the arm shape that you're not going to use and do the same thing on the other side.

Step 6: The Robots Legs

The robots legs are probably going to be the hardest part not to break. But I have a solution to not cutting them off and/or breaking them off.

First though you're going to have to decide where exactly you want the legs to be and make the cuts like we did on the arms and head. But this time you'll put a pin in each of the legs and inside the cuts you made. This will keep you from cutting off the legs and snapping them off. Because when you're cutting down while it's on its base like a prism you will hit the pins you put in the cuts so you don't cut off the legs. You don't have to do this, of course. But it does help. By now I hope you know how to cut the legs out, since you already did the same thing with the head and arms.

In case you don't know though, put it upside down so it's legs are facing up. Then cut down to his body where you want the legs to be. And then cut close to the body down to where you cut where you wanted the legs to be.

Step 7: Shape His Body

Now he'll have a head, arms, and legs, but not a robot shaped body. It will be robot shaped on the sides but his stomach and back will just be pretty much cubical.

For the front of him if you cut a triangle off starting right in front of his neck and smooth the edges. Towards the bottom you might want to cut off a bit to make it more smooth and rounder. Mine ended up not too round and sorta tilted to one way

Then for the back just cut off more than you did for the front and round it a bit.

You'll probably have to cut off some small pieces to make it smoother and stuff.

Step 8:

Since it would suck a lot if you had spent all this time making the Instructables robot and then accidentally squished his head in or something or put a hole in his body it helps if you coat him in a layer of Plaster of Paris. This green foam stuff gets dented really easily.

So just mix some Plaster of Paris with water so that it's just thick enough to paint on with a paintbrush. If you want to cover the green completely you'll probably have to go over it a few times. Also, for his red ear thingies you might want to put some thicker plaster on the sides of his head.

Once it's dry it's ready to paint! Unless of course you want to sand off some lumps and stuff.

Step 9: Tips and the End

Well once you've painted it you're pretty much done. You could still make a base for him though so he stands up well by taking a rectangle of foam or something and putting pins with flat heads through the bottom and into the robots feet. You can also use flat headed pins for the antenna like thingies that stick out of the side of his head.

Anyway here are some tips that might help you:

Don't drop the cup of plaster under the porch.
If you're going to do this outside you should do it someplace protected from the wind.
Don't hold the robot by his legs while you're painting plaster onto him
Go slowly. In the end it will look better.

Have fun making one :D And if you do make one I would love to see a picture!