I dismantled a 240V soldering iron heater. All these years I thought it
would disintegrate into a pile of mica but now I see the secret, should
be no problem making one. How do you form mica into a tube, simple. You
part score mm apart lines into the material, then it will roll neatly.
This one accepts a magnastat tip so may even be reusable in itself with
the right resistance wire for 24V 50W instead of this one of 4,000 ohm .
Mica tube 6.7 and 5.8mm diameters as a former and 2 layers of wire with
an interlayer of 10x35mm scored sheet of mica rolled up, terminals just
clipped over the central core.