While only one walker was ever shown to the world it is known there were other versions in development or at least planned.
These pictures are from the original drawings, they have been cleaned up and increased in contrast to make them clearer.

These are not production designs (which would be a lot more complex), I think they were trying out a few different variations to see how they would look.

This is the only "Artist's impression" type drawing.
I can imagine this would not have got a good public reception, it has a rather unfortunate resemblance to a waste bin!

This is a simplified Technical drawing of the above,

This is a shorter, thinner version of the Walker, it's also only a one piece case.

They were also trying some ideas for Keyboards, these are both based on an A4000 keyboard layout whereas Amiga Technologies announced they intended to use a standard PC keyboard.

This is the closest to the existing Walker, the ports at the back have been moved around and there appears to be additional expansion in the form of two sideways slots.
The keyboard connectors at the front have been moved down to the motherboard level.

This takes the previous version and adds a middle layer giving room for many more extra expansion cards.

Amiga Walker Front Page.