Ravignat (see further reading) gives no source for his “90th Degree: Supreme Grand Council General of the 90th and Last Degree, Sovereign Grand Princes of the 90th”, but I think it (partly) comes from Fonds Gaborria Ms.-372: “Rite de Misraïm. Les 3 suprêmes conseils du système d’Arcano, Arcanorum des 88e, 89e et 90e degrés, 17e classe” which contains three “Arcana Arcanorum” degrees.
Ravignat’s text bluntly states: “Tracing Board: The Alchemical Hermaphrodite:” which is followed by the image below. There is no such image in Ms.-372. But perhaps the author of the degree assumed that everybody knew what image he referred to.
Ravignat gives as source for the image that he used: “Rebis from Theoria Philosophiae Hermeticae by Heinrich Nollius (1617)” with which he follows other such source references online. That book can actually be found online on a few places but this image is not part of it. It actually comes from Viatorium Spagyricum by Herbrandt Jamsthaler (1625). This book can also be found online and that is where I got my image from.
Thus, it is not certain that this very image was used as a tracing board in old “Egyptian Freemasonry”, but there is a strong suggestion that this, or a similar image, was.
Viatorium Spagyricum by Herbrandt Jamsthaler (1625)