I would personally prefer 6 MM Eva mould made from PU like a prefect boxing gloves.
If buy a crystal chain, you can even examine whether the holes among the beads are smooth and round and whether the sizes belonging to the holes are equal. https://Www.digitaljournal.com/pr/news/press-advantage/contractors-state-license-center-is-offering-classes-for-contractors-license-in-los-angeles