A hollow bead is made by creating two thin disk beads close together, and curing towards each other. Creating two dome-like structures that curve towards each other. Then, finally, they are connected. The hard part is making sure there are no holes. Because, you see, as air is heated it expands and if there are holes, well, the air escapes. If the air escapes, the bead will collapse and no longer be hollow.
Easy to explain, but hard to picture, so I'll include a video I found on YouTube. Isn't YouTube great!! (She's listening to Pearl Jam, nice song)
Hollow beads are great for creating larger works of glass because air is light, and a larger bead will be lighter too. Nice for pendants. And perfect for my handmade fish beads! This adorable guy just might still be available in my ArtFire shop. Click on him to see.