PlacementPreview

Placement Preview is a mod that lets you know how your block will (probably) be placed beforehand. Simple as that.

Look at the following screenshot to get an impression about how it works:

You can press Shift+R (by default, configurable) to disable this preview.

No, I wasn’t aware of another project with the same name until CurseForge tells that the project name has been taken. Differences:

• This one starts from scratch
• This one is small enough
• This one targets newer Minecraft version.