No idea if you ever read MacAddict back in the day, but I remember back in 1997 they actually interviewed the guy who built the very first 6400 prototype - "Hacksaw". They had a pic of it - it was basically a 6300 with no case plastics on its side, modified so that it was about as wide/thick as a CD-ROM drive, allowing the CD-ROM drive to be installed horizontally with the Mac on its side.

For what its worth, all these years later - I still think the InstaTower is sexy...though I have bad taste.