With Tesla making 21700 cells by the millions, it is only a matter of time before they replace the 18650. If you don’t have Tesla cells, you can buy 21700 cells from Queen Battery.
This Bloc holds twelve 21700 cells, in two groups of six in parallel. Connect Blocs in series to multiply the voltage. Whenever you order multiple Blocs, I assume you are going to connect them all into one battery. I include the necessary series connectors and also the ring terminals for connecting wire leads.
If you are making multiple batteries please let me know so I can send you what you’ll need.