Now, after seeing this last picture in the description of the giant stalk creature, you may have said "forget the snake thing, but I like those tentacles in the background!" Fortunately, those are easy and cheap to make.
I laid down a large piece of wax paper over a 6 foot long two-by-four then drove two nails into each side of the board. I spaced the nails less than a 1/2 inch apart. I then tied two pieces of string to the nails as shown and pulled them tight so that the strings were held up about an inch from the board (leave about 6 inches of extra string at one end). I wadded up two to three small balls of plastic wrap and placed them under the strings. These will act as joints so that the tentacles can bend.
I then carefully put down Great Stuff spray foam over the string, stopping at the plastic wrap. After the spray foam dries (about 2 hours), remove the nails, trim the plastic wrap (or remove it totally) and paint. Use the extra string you left at one end to tie up the tentacle. Note that after a day, the tentacles will start to curl some (which I found desirable).