Gift ideas for glassblower

My dad has been attending a glassblowing class for the past 6 months or so, and his birthday is coming up, so I was wondering if anyone had any recommendations of gift ideas for a glassblower. He’s obviously still somewhat new and attends a fairly kitted out place, so if you know of any more obscure but still nice-to-have equipment or other, that would be very helpful.

Thanks in advance!