Acme Disappearing/Reappearing Ink is a product of the Acme Corporation and used by Marvin Acme to write his will in Who Framed Roger Rabbit. It's a special type of ink that can (as the name suggests) disappear and reappear at almost any time.

Who Framed Roger Rabbit

Media: Who Framed Roger Rabbit | Tummy Trouble | Roller Coaster Rabbit | Trail Mix-Up | Bonkers Characters: Roger Rabbit | Jessica Rabbit | Eddie Valiant | Dolores | Judge Doom | Smart Ass | Greasy | Wheezy | Psycho | Stupid | Baby Herman | Benny the Cab | R.K. Maroon | Marvin Acme | Lt. Santino | Bongo the Gorilla | Toon Bullets | Singing Sword | Toons Objects: The Dip | Acme Disappearing/Reappearing Ink | Marvin Acme's will | Toon Revolver Locations: Toontown | Cloverleaf Industries Songs: Why Don't You Do Right | The Merry-Go-Round Broke Down Disney Parks: Roger Rabbit's Car Toon Spin