I buy the JST-XH extention balance leads from ebay as hobby king is normaly sold out, the magnets i get from ebay., the rest is a mix of ebay and hobby king and i normaly have most stuff like heat shrink for my rc and car hobby.
There is a list of stuff i use here on post number #43 and there is a very quick run down on how to make them on post #88
https://budgetlightforum.com/t/-/3118
On this thread there is some nimh (AAA, AA, D and C) battery holders i use for charging with my hobby charger, there is some of my picturers on the first page but the info and links start on post #74
https://budgetlightforum.com/t/-/1621
This is a link to hobby charger assesories that didnt go far
https://budgetlightforum.com/t/-/4411#comment-108825
This is a link to charging 26650 batteries, but you can use the same setup as my balance charging thread to charge any size li-xx type batteries
https://budgetlightforum.com/t/-/7455#comment-150151
Shadowww the 6s extention leads you have posted are way to short they would need to be extented or by the 45cm jst-xh extention leads to start with.
Any balance set up over 2s needs more then 20cm of lead 3s needs around 30cm, but you can cut them, joint, them solder them together cover the joins in heat shrink and so on or just buy longer balance leads to start with.