I'm in the process of making a sideshow-style gaff of a "Kraken tentacle". The basic technique is identical to the one in the original "Making a Tentacle" tutorial, but veers off a bit from the "Tentacles: The Suckering" followup. This approach produces much more realistic suckers by using short lengths of aquarium tubing attached to the main body of the tentacle.
The materials I'm using are cheap and readily available- plastic cling wrap, latex carpet adhesive, floral wire, acrylic craft paint, aquarium tubing, and polyfill fiber stuffing. All together I think everything cost around $15, and that provides enough material to make quite a few tentacles. That's an important feature, at least to me, because I make up for my lack of artistic talent by taking advantage of iteration. Do something enough times, fixing the mistakes from earlier versions and improving your technique, and you'll eventually get great results.
If you haven't read the earlier tentacle tutorial here's a quick recap: the main body of the tentacle is formed from polyfill fiber rolled out in an elongated cone shape around a floral wire core. That in turn is wrapped in layers of cling wrap plastic to give it a firm body. The whole thing is then coated with layers of liquid latex colored with craft paint to provide a final surface texture.
This particular tentacle is a test run using lengths of aquarium tubing as suckers. The tubing was trimmed with a razor knife and then fixed to the body using liquid latex. The latex doesn't adhere to the tubing particularly well, but one of the wonders of liquid latex is that it bonds to itself magnificently. You can coat the tubing with a rough layer of latex, let it dry, and then take advantage of that mechanical bonding to attach the tubing. Once you apply a few more layers of latex the suckers aren't going anywhere.
Here's a look at the results. Just click on the picture to see the large version.
Since this was just a proof-of-concept test I didn't finish the ends of the tentacle and you can see the exposed cling wrap that forms the foundation for the skin. The suckers look pretty good, but I probably should have added another two or three sets to do a better job of filling in the body. You can see how the tubing sections start very short on the left and steadily increase in length as you move to the right down the length of the tentacle.
To the left you can also see the result of another technique I was testing. The small horns or scales were created using drops of liquid latex applied with the tip of a sharpened pencil. As you pull the pencil away the surface tension of the latex draws it to a point, creating the tooth-like spike. You can produce some amazingly detailed texture effects like this, effectively "painting" three-dimensional structures onto the skin.
Here's a closeup shot of the tentacle.
One of the things I love about this method is the gnarly organic texture of the skin. It naturally develops as you apply the latex with a sponge. With a dark glaze and some light drybrushing it would really pop, but even in this monochrome state it's pretty impressive.
With this test finished it's time to move on to the next iteration. I'll fix the problem with the sucker spacing by adding more sets, and try to give the tubing a more organic look. Using a heat gun to flare the ends and add a little irregularity to the perfectly round shape should help with that.