During the Majin Buu Saga, Supreme Kai used his powers of Magic Materialization to summon a block of Katchin to test the Z Sword. As Goku hurled the cube at Gohan, the Z Sword proved no match for the cube of Katchin, and thus the sacred Z Sword was broken, becoming no more than a dagger and releasing Old Kai.
In the future, Supreme Kai summoned a block of Katchin to finalize Trunks' training in preparation for Babidi's arrival on Earth. As Supreme Kai about to toss Trunks the block, Kibito sensed Babidi's movements so the Katchin was not used.
Video game appearances
In Dragon Ball Z: Buu's Fury, there is a wall made of Katchin in the Cave of the Ancients on Grand Kai's planet. Unable to break it even with a kamehameha, Goku uses Instant Transmission to pass the wall and get the ancient artifact hidden inside. Later in the game, Supreme Kai makes a block of Katchin appear in order to test the Z Sword like he did in the manga/anime.
In the Budokai series, one of the Supreme Kai's special attacks involves him summoning a block of Katchin and throwing it at his opponent (technique called Supernatural Abilities in Budokai 3). In the Budokai Tenkaichi series, the block is used in the basic rush of the Supreme Kai. In Dragon Ball Z: Budokai Tenkaichi 3, Supreme Kai's downward hypersmash is hitting the opponent with a block of Katchin.