You will need a pair of black socks, grey pieces of clothing, one black piece of clothing, masking tape, some balls of crumpled paper, shreded toilet paper, some surface for your devourer (I used a clipboard), colored yarn and a needle.
Take one of the socks and start pulling it inside out, stopping halfway. Fill it with the crumpled paper balls.
You should now have something that's maleable but that can still retain its shape (if not, stuff more paper in the sock). Use the masking tape to attach the sock to the clipboard, making sure the opening is on the downside, so the paper can't fall out.
For the fangs of the devourer use toilet paper and use the masking tape to aid you. In the end add a strip of toilet paper to hide the places where you used the tape.
Add more strips of toilet paper along the devourer body (don't use tape here, it's not necessary and it's hard to hide)
Here I thought the strips were too wide so I cut them down and crumpled the paper slightly to give it a more jagged look.
Now we add the pieces of clothing. They have 2 purposes, hiding the clipboard and the tape holding the sock to it (use the black one for this), as well as working as a background (use the grey ones). I used tape to keep the grey shirt in place.
Now take the other sock, stick it in the mouth of the devourer and use the needle to keep the socks joined. You may have to reinforce the tape in the back of the devourer because of the added weight in the front.
Place the colored yarn and we are done.