Be careful if you’re planning to cut or modify a helium tank—it’s crucial to ensure it’s completely empty and properly purged before working on it. A horizontal split with a hinged lid usually works best, as cutting the ends can make insulation and refractory placement tricky. I’d recommend lining the interior with ceramic blanket and a thin refractory floor for heat retention. Some builders also fill gaps with perlite for extra insulation. For inspiration on safe and well-designed helium setups, Ballooné [commercial link removed] has some great ideas for handling helium tanks safely. Always prioritize safety when working with pressurized tanks.