Item transparency slider!

The ability to make an item opaque, semi-transparent.

Example, you can make a chest look semi transparent, like a ghost.

My personal example.
I wanted to create a force field effect, I can make a large glowing magic ball, which works, but i would like to make it semi transparent so that you can just see whats behind it

It could also be used for things like portals/magic doors/ghost npc's and so on. (even for magic projections or 'ghost reflections' in a mirrored room)