At the moment (2021) not much is known about the exact instruments that Hand Reichel built, with the exception of the Daxophone, which is a well documented instrument with many copies being made by various makers around the world. Reichel made many experimental guitars which are poorly documented.

The Daxophone is by far the most famous instrument built by Hans Reichel. The instrument has become a sort of icon for the experimental musical instrument world and is one of the few to be openly adopted and played by many experimental musicians. Part of the success of the Daxophone can be attributed to the detailed construction guide that Hans Reichel made.

Here is the Daxophone Information PDF taken from the now defunct Daxophone website. This document details the construction process for a Daxophone. I have taken the liberty of hosting it here since the original website is difficult to access (see notes). ¹⁾

In the 1989 article ²⁾ the daxophone is called a “dachsophone” and claims that “dachs is German for “Badger””. It is very likely that at this time the early version of the instrument was called a Dachsophone. The article also strongly suggests that the Daxophone was invented in 1986, which is the same year as the below video, which demonstrates a very early performance of the instrument. Note the rather underdeveloped technique and sound as compared to later recordings of Reichel.

There is some recordings of this instrument as well as this short video shown below.

Two instruments are detailed in the 1989 article ³⁾, one with an acoustic body and one called the “Stick” which has no acoustic body and is generally stick shaped. These two guitars utilize a 3rd Bridge.

There are two guitars depicted in the 1989 article ⁴⁾ of guitars with additional frets added that go so far as to act as bridges across the sound hole of the guitars. These may represent some of Reichel's early experiments with playing mas many harmonics as possible on the guitar.

A short narrative about Hans Reichel by Daniel Fishkin and that details making a Daxophone in his studio ^{5) 6)}
Part 1 Introducing the Daxophone by Daniel Fishkin⁷⁾
Part 2 How to Build a Daxophone Soundbox by Daniel Fishkin⁸⁾
Part 3 The Mystery of the Acoustic Cantilever: Building a Dax for Your Daxophone by Daniel Fishkin⁹⁾

Again a link to the original PDF on how to build a Daxophone ¹⁰⁾

Crossing the Bridge by Hans Reichel, by Joe Gore that appeared in Guitar Player Magazine, 1989 ¹¹⁾
This article details the names of many of Reichel's early instruments

The original website daxo.de is not readily available because it was running adobe flash, if you have the ability to view the website using a lineage viewer, the original website is still viewable ¹²⁾
Here is a youtube video detailing the website as it was intended ¹³⁾

I find the video of Reichel's Pick-Behind-the-Bridge-Guitar really fascinating because the video is from 1986 which seems early for experimental guitars like this. This is a point that needs more research as I also think Bart Hopkin and Yuri Landman drew inspiration from these experimental guitars.