You can add items, blocks, textures etc. on GUI.

Use Registry Book at the last of misc creative tab!

Registry Menu Adding a block model Adding a cage block model Block List Place blocks to your world!

Notes:

This is a both(client and server)-side mod.
Feel free to use this mod in any modpacks.

Mod compatibilities:

Preparing now...

Mod Incompatibilities:

VintageFix