Was already at Joann's to pick up some fleece for a future project, and perused the nylon, which was on sale. Picked up a couple yards and went home to make a basic tentacle...which I then hooked up to a fan, just to see if and how it would work. It failed spectacularly in that it barely filled up with air--the fabric was just too heavy. This (unfortunately) didn't discourage me. I combed the internet for material used to make the Halloween inflatables (they're annoyingly non-specific other than "weather resistant polyester") then moved onto hot air balloon material (usually sold in super bulk, and in pretty uninspiring colors).
Then I had the thought of garbage bags. MUCH lighter than fabric, DEFINITELY waterproof. The colors were a concern, but then I remembered that Mom occasionally has random colored ones from NPS and various other sources. A quick phone call revealed that she did indeed have orange ones, and they were at my disposal.
The next question was how to create a tentacle shape. Obviously duct tape was an option, but might weigh down the whole thing. Then I considered the possibility of sewing it together. Taking one of my own white garbage bags, I experimented with sewing a straight line up the edge to create a basic tentacle shape. I used larger stitches, and went slowly to ensure that it didn't mess up my machine. TOTALLY WORKS!!
Having proved that it could be done, I went about cutting up the orange ones. Three got sliced down their sides to create 3 long narrow pieces, and 2 got cut so that it created a more square area.
The narrow pieces turned into tentacles with a line up their sides that progressively narrowed to a point.
I then pinned one side of each tentacle base (now turned inside out to show the 'right' side) to one of the squarer pieces with 'right' sides together. Did this with the other side as well, making sure to sew together any large holes between 'fabric'. Put this up to one of my larger fans, and turned it on.
Couldn't get a proper picture of it because I had to hold it up to the fan with one hand, but will post one when I get the box fan and can secure it properly.
I can already tell there are some tweaks to be done. I think I'll narrow the tentacle size just a bit, just to make it easier for the fan to fill up the air bags--though I'll wait until after I try it with the final box fan I'm intending to get. I'll also put feet or some kind of risers on the fan so that air can still circulate when it's placed on the ground. I'd also like to figure out a way to curl them a bit to look a bit more tentacle like--maybe tack them to themselves at a few points, or a thin wire--maybe even a small amount of tape. It depends on the strength of the fan and what it can handle. Also if I can draw or attach on something for suckers, that would be ideal.
Little difficult to see how it's sewn together, so here's a (slightly) more demonstrative diagram.
Green are the narrow tentacles. Blue and purple are the square pieces on either side with the tentacles sandwiched in the middle. Pink is where the sides of the square pieces were sewn together after everything else.
I mocked up how it will basically work using the original white trash bag model and a much smaller fan. The result was pretty good.
Made the tentacles narrower to decrease the space the fan would have to fill...better, but not what I was going for. A possible solution would be to tip the fan on its side so that the fan blows out down the tentacles better. Or maybe wire that forms the tentacles better? Or maybe even putting slits towards the top to have the tentacles partly blow up--once they were full with air they immediately fell over. Will have to experiment. The only bummer thing is that it's hard to undo things when you're dealing with such delicate material. Trying to take off the duct tape (to stick to fan) was a futile effort--had to just cut it off.