How do I use air or water pressure to make flexible tubing rigid for costume wings?

I'd suggest thinking about using springs or pulleys in addition to the water system. They can help manage the movement and take some load off the pump. If you go this route, it might give you more control over how the wings move.

Don't underestimate fans! Using a few small fans can help create some interesting movement for your wings. It's a different approach, but it might add a fun airiness to the effect.

Just a tip: keep experimenting with the size of the tubing. You want it to be small enough not to add too much weight, but big enough to handle the water flow needed to make those wings pop out!

For this kind of project, lightweight tubing is key. Look for thin water tubes that can handle pressure without being too heavy. You might even consider using some lightweight materials like plastic or rubber. If you want something a little different, remember that sausage casings can be surprisingly flexible! Also, ensure the wings are light enough to lift easily when the tubing is filled with water.