Glass ships in bottles are made of borosilicate glass. This type of glass is strong against thermal shock . . .
Regardless of time and make, glass ships in bottles consist of common stylistic features, including the ship's body, masts, sails, rigging and the bottle itself. Sails are invariably made of glass tubes sliced into small sections. The curved surface of the original tube lends itself to the depiction of billowed sails. Some patterns can be added by sandblasting, and they are sometimes fumed with gold.
Larger diameter tubes are used to make the bottles, thick rods become the ship's body and thin rods form the masts. The manufacturer of glass ships in bottles was largely instigated by newly redundant scientific glassblowers because these design features implemented the economic necessity of consuming surplus stocks of rods and tubes.
Put the sails on to the masts, then fuse the masts on to the ship's body. Various home-made hand tools can be used to emboss patterns to represent windows and the like. For example, metal files and screws can make very effective textures. When rigging the sails, extra attention has to be paid so that the sharp flame does not catch the sails or the ship body.
Place the ship inside the bottle via the open bottom, and hold it in position with corrugated cardboard. Heat the spot very well on a vertical flame until the join becomes smooth. Check from all angles, making sure that no deep creases or sharp ends are left. In the end, close the bottom of the bottle.