If I want to “draw” a design such as green swirl on a red bowl would I use a round blank and glass powder to draw it in like sand art?
You can draw onto the glass with a Sharpie and it will burn off during the firing. Apply glue on the glass and fill it in with frit to keep the design where you want it or design it like a mosaic with small bits of glass. You can also use Glass Multipens which are writer-tipped bottles of liquid glass that may be used to create designs on glass prior to firing.