Extra Pieces is a mod for the Fabric Mod Loader for 1.14 versions of Minecraft.
It adds Stairs, Slabs, Walls, Fences, Fence Gates, Sidings, Corners, Posts and Columns for any block you want!
What are Sidings? Vertical slabs.
What are Corners? Sideways stairs.
What are Posts? Fences that don't connect and can face any axis.
What are Columns? Walls that don't connect and can face any axis.
Any block I want? Yes!
By default, the mod creates all of these 'pieces' for a considerably large amount of vanilla blocks, but it creates them based on a config! (found in the config directory)
The config may look daunting at first, but if you take your time to look at it, it's quite simple. A full explanation of it (and maybe even a tool to help you edit it) will be coming eventually.
Have fun with unlimited block shapes!
DISCLAIMER: This is NOT a Forge mod! It does not work with Forge. It uses the Fabric Mod Loader (found here) in addition to the Fabric API.