FishAus and I have been making mods for the server we play on and wanted to share some of what we have learned along the way. (FZM = FishZeelMods, original, we know.) You can find me on Discord, Zeel Nightwolf#7289. You can get in touch with FishAus, FishAus#0367.
So far FishAus has created 2 tutorials which you can find on the EcoModKit/wiki. The first tutorial takes you through the steps on how to create new constructable blocks (similar to Hewn Logs). The second tutorial then shows you how to then use the Custom builder to change how the blocks react when next to each other (so you can make corners).