I have made fire hats with single flames and multiple flames. Depending on your design (one flame, two or more) you will need more or less of the pneumatic and brass fittings.

Per flame you will need

One length of metal tubing

One pneumatic elbow

One of each of the brass compression fittings

One pneumatic muffler.

If you decided to go with multiple tubes, be aware that symmetry is possible but a real pain in the butt.

Cut a length of your metal tubing (copper or aluminum) about twice as long as you need it. The extra length will help with bending. Your tips need to point up. As tempting as it is to have streamlined tips pointing back, don't do it. Fire likes to go up, so let it do its thing.

Heat will build up and move down the tubes. Heat is less of a problem with aluminum but a factor with all designs. Choose tube lengths that work with your comfort level.

Once the tube is bent to meet your design, use the pipe cutter and trim it to size.

Attach the brass compression fittings to each end of your tubes.

Apply yellow teflon tape to all the threads then attach the pneumatic muffler and the pneumatic elbow.