May of 2020 I made a tutorial for using the DRI (now DBS) KitPCB battery building kit. That’s finished, and still a good resource, though it’s pretty product-dependent.
February of 2021 I made “Part 0” of a complete custom battery building tutorial over on the FreeSK8 forum, which was planned to be many, many parts. That project died when I realized how much time I would have to put into it in order to make it something I feel comfortable directing a noob to and saying “this is all the info you need”. The scope just got way too large to be something I can take on, while also trying to run a business and pay my bills.
I hope to be able to get back to it one day, because I feel that a tutorial of that nature is desperately needed. They have something like that over on Endless Sphere, which I have read through, but it’s not the most user-friendly format or forum, and it lacks some of the safety standards we hold ourselves to these days, particularly for esk8 batteries.