The vases are made from pieces of flat glass. Some are just plain old window\plate glass and some are the types of colored glass one might purchase from a craft\stained glass window supply store. The vase parts are pre-fab, cut to shape with the edges ground smooth. The curvy parts are slumped into shape. They have templates for the vases or you can be original and create your own vase design or some sort of sculpture or whatever and for those you are charged by the piece. They use some type of quick-set clear drying glue\adhesive to put them together.
If you like that sort of thing maybe you might be interested in slumping glass as a hobby or make things to sell. ebay is loaded with auctions selling supplies, especially the slump molds which come in many shapes and sizes. Of course you will need a kiln or know someone who has one they will let you use. The energy cost to fire up the kiln can be expensive, so you need to squeeze as many projects as possible into it at one time rather than just do one project at a time. Also; the kiln process is time consuming, up to 40 or more hours in some cases, depending on the type of glass you use, how thick and how much. The glass has to be heated up slowly and then it also has to be cooled just as slowly. I wouldn't mind having such a hobby if I could afford it and was sure I could sell the items I made for enough profit to support the hobby.
The piece I made is okay I guess, yet I'm more interested in experimenting than I am in making dishes, vases etc., but I'm stuck using the molds they have on hand which are for those items. I would like to design and make my own molds, but that's yet another expensive, time consuming thing I want, but can't have lol! You can even slump already made pattern glass plates, made by dishware manufacturers. The glass only softens enough to slump\sag down and take on the shape of the mold, but the pressed in pattern is barely effected.
Life just isn't long enough to do or try everything I'm interested in ;-( Mike