No-chambers were constructs that hid whatever was inside it from prescient/oracular vision. It also appeared to render the contents invisible and undetectable in other ways.
The first type of no-chamber was invented by a scientist named Tenu Chobyn prior to the ascent of Paul Atreides. According to these sources, Chobyn created his type of no-chamber for the Baron Vladimir Harkonnen, and that it was built by the scientists of House Richese. This subsequent technology was lost in the destruction of the scientist's work area on the artificial moon of Korona during the Great Spice War.
A very similar technology was invented by the Ixians and was a combination of efforts on other devices such as a device that recorded the thoughts of Leto II into a written journal, a device that hid the journals from prescient vision, and experiments that created a navigation machine that replaced a Spacing Guild Navigator. The first of these new no-chambers was constructed on Ix. Inside this chamber Hwi Noree was grown by the Ixians with biological technology they bought from the Bene Tleilax.
The no-chamber technology was later incorporated into the no-ship.
Behind the Scenes: Chobyn's "No-Chamber" Edit
It is suggested in Brian Herbert and Kevin J. Anderson's Prelude to Dune prequel trilogy that the first no-chamber invented was the no-chamber the in which Duncan Idaho and Miles Teg hid during their escape from the Bene Tleilax on Gammu.
The origin of this inconsistency is a paragraph in the UK edition of Heretics which appears to imply the no-chamber is pre-tyrant ("Teg guessed it to be much earlier than that of the Tyrant"). However, this is not the case - when read in context it becomes obvious that this refers to the Gammu chamber pre-dating Leto's own chamber - Leto himself let them build it.
Kevin J. Anderson explained this in a 2007 interview, saying "Chobyn was killed and all records of his work were destroyed, and the technology was lost. There is nothing to suggest that these two are the exactly same technologies." The chamber in Heretics is not the chamber in the prequels.