Working glass by applying heat with a torch is called ‘Lampworking’. When a lampworker wants to blow glass he would normally start with a tube of glass with an attached blow tube. He rotates the glass very consistently in the flame and then gently puffs and shapes it into what he or she wants.
There is something marvelous about glass. It can behave like clay, stone, honey, wax and have a continuum of plasticity by just changing its temperature. I sometimes us a common ‘butter knife’ to move the glass around as well as razor blades, picks, tweezers, pliers. You can use any tool that does not catch fire and does not leave a residue. Graphite is probably the most used substance for sculpting glass. It does not melt and does not leave much of a residue.