Don't mind my pirate ship, this is only a week long temporary fix for me lol.
I made this because I bought a new regulator and the diffuser I had wouldn't work with the diffuser I had. (The regulator had to be set to 30psi for the diffuser to work and the regulator I bought was automatic.) I needed something cheap since it was only going to be for a week. It suprisingly worked really well and made the bubbles super tiny just like a diffuser so I figured I would share this with everyone!
Take a cotton ball and wet it. Place the cotton over the end of the tube. Use a piece of micro-fiber cleaning cloth, like the kind you get from the cell phone screen protector kits, and place that over the cotton ball. Pull down on the cloth as hard as you can and zip tie it. If you have a pair of pliers available, use those to make the zip tie as tight as you can so it is less likely that air will escape from below it. It works better when it is pointing upward (hence my pirate ship lol)
**I had to redo it like 4 times to get the cotton ball just right to make the bubbles micro size, but I eventually got it set correctly, so anticipate on having to do it a few times!**