From amiga-news.de:
1. The Amiga Walker has not been designed by Frog Design, but by the greatly talented designer Daniel Gilgen on behalf of Stefan Domeyer for my former company KS Design in Frankfurt, Germany. The idea to expand the Walker step by step until it becomes a tower finally originates from Daniel Gilgen. He was the one who built the prototypes for CeBIT from the master design model which I do still own.
The Walker drawings I have do indeed have Daniel Gilgen & KS Design listed on them.