Perhaps it’s a manufacturing rather than design problem, but it seems that every time I get it out to use it, another cone has cracked, allowing the section above to move freely. Tightly applying duct tape helps, but there is only so much duct tape in the world!
I’m not surprised they don’t last long. They’re not meant to hold any weight, and they’re a disposable. They’re for stuff like this, and you’d usually expect to change it regularly (depending on quality of the shop).
I have this set and they are quite expensive but durable.
I just found this on AliExpress:
NEWACALOX Soldering Third Hand Tool PCB Holder with Magnetic 4Pcs Flexible Arms Crafts Jewelry Welding Workshop Helping Station