I’m not certain what others call a “hankerchief mold” but I have used a “floral former” mold and achieved much the same results, judging from the picture. A floral former is basically a stainless steel mold (prepped by prefiring to 500 degrees and spraying with kiln wash or there is a commerical product you can buy and spray on at room temperture, whose names escapes me now but it works wonderfully) or you can use a s.s. cocktail shaker turned upside down (or elevated with taller kiln posts as necessary). The glass is slumped over the top (really the bottom – the end which is not open) but one must watch the process rather carefully to cut the heat before the glass collapes too far or (horrors) drapes itself onto the kiln shelf (this is where the kiln posts come in). One could also use a larger ss. circle on top on the mold to have a larger “base”, I would suspect. They make great candle holders and are quite “slam dunk” to make. Hope this is helpful,
Windows listen attentively for the sound of broken glass.