It would be neat to be able to use EMC from ProjectE with this.

What should be the expected behavior? I would guess that wands should be able to consume EMC from a tablet in the players inventory if the required block can be created by it.
ProjectE does have an API, so it should be possible to do that.

ProjectE Alchemical bags also have a different interface than standard containers, so they will need a special handler as well to be usable with ConstructionWand.

I am currently learning for some exams, so you will need to wait until I find the time to implement this. Maybe I'll publish it once Forge 1.17 comes out together with the 1.17 update.

No worries about the timetable. 👍

Yes, this is what I was hoping for "I would guess that wands should be able to consume EMC from a tablet in the player's inventory if the required block can be created by it.".

Thanks