This one is kind of a joke and an experiment in just how cheap you can build a guitar. The body is dry-erase board over plywood - no finish - with Tolex side binding. Dry-erase board is Masonite covered with Melamine. The neck is 100% Radiata pine, even the fretboard. The "inlays" are glitter and CA glue. The pickguard is the other side of the dry-erase board - 'chalkboard'. The pickup mount is a 57 cent switch plate.
A conversion neck is one that can convert an instrument from one scale length to another with no other modification. A common conversion is 34" to 32". By overhanging the 20th fret, or leaving it off, you can use the stock bridge location on the body, just adjust for intonation. Such a neck will work on any standard bass body. A conversion from 34" to 30" requires overhanging two frets, or losing one or both.