By far the hottest place I've ever had to work in my life. This was a rather simple design, but testing this thing out was a testament to my commitment to ensuring my designs work. If you eyeballs weren't boiling, you weren't doing it right.
When molten glass tube is extruded through a mandrel and redirected, small roller marks can be left on glass with heavier wall thicknesses and outside diameter. I devised a nozzle to attach at this point to serve the dual purpose of cooling the outer skin prior to roller contact and creating a cushion of air under the glass catanary. When it wasn't throwing the glass out of spec, it did a decent job.