the.com/mandrel
the unsung steel spine that lets hollow metal hold its shape under brutal pressure
core jobSupports tubes from inside while they're bent or formed
name rootLikely from French mandrin, a lathe spindle
hot workGlassblowers wind molten glass around them for beads
battery trickCylindrical cells coil electrode layers on a mandrel
vanishing actSome dissolve away after composite parts cure