A Creative Fluid Storage Disk is an item where items from the storage system are stored on. It has to be put in a Disk Drive.

The Creative Fluid Storage Disk won’t despawn when dropped in the world.

Uncrafting

Sneak and right click while holding the empty Creative Fluid Storage Disk to retrieve the various parts back:

Storage capacity

The Creative Fluid Storage Disk can store an infinite amount of buckets.

It can only be obtained in creative mode.