Describe your suggestion

When you build and the build fails because you don't have all the blocks, adding a ghost-like semi-transparent texture of the needed items in your inventory would be nice.

Settings

#previewBuildItems

Context

Most users are confused when building fails, adding a visual way for them to understand how would be immensely helpful in reducing the amount of stupid issues that are created.

Final checklist

• I know how to properly use check boxes
• I have not used any OwO's or UwU's in this issue.

Maybe just a list of items in chat, if you click on one item B mines it

There is an existing mod that can make this type of "material list" that appears as a hud on the screen and display what items you need to acquire to have all the mats. It can handle shulkerboxes with items in it. The name is Litematica (similar version of Schematica but more developed and much better).
It's a mod by masady, you can find it on github too or in the scicraft discord for more infos

Litematica isn't compatible with Baritone to my knowledge, and doesn't run on Forge.

yes it's incompatible with Baritone but runs on forge 1.12.2 but I just wanted to point out that it's possible and maybe the code is public

You can use Schematic2Blueprint in order to do this.

Yes, litematica+baritone would be an awesome auto-building combo! No need to do any semi-transparent previews in Baritone, it's better to make a litematica integration, where Baritone could build litematica schematic placements. You would also be able to set position and rotation of your schematics too! Also with litematica you can save schematic in place, so you can disconnect, then connect later and continue building.