I found a wealth of useful (and some not-so-useful) information about DIY e-bike building on YouTube. Below, I’ll share several links those videos I found most helpful:
Electric Bike Conversion Kit Options from Electric Mountain Bike Network
A budget Voilamart rear-hub build video from GoldGuy
And another from Side Project
And another from Expedition-Electric
And more: https://www.youtube.com/results?search_query=diy+rear+hub+%2B+voilamart
Hub Drive VS Mid Drive eBike motor systems from Blue Monkey Bicycles
US Electric Bike Laws Explained from Bolton Ebikes
Interesting nugget in this video at 3:46 where he says “A low speed electric bicycle (<750 watts, <20mph ‘when powered solely by the motor’, and operable pedals) shall NOT be considered a ‘motor vehicle’.” This is important because federal law trumps state law. Therefore, the state cannot classify this (Class 1 or 2) electric bicycle as a motor vehicle.
Also from Bolton Ebikes, How to maintain Lithium batteries for electric bikes
As I come across them, I’ll add more videos to this list…