Slide rule workshop AK

Peter Hopp's second mystery slide rule

Mechanical Engineer Pocket-Watch slide rule

Click images for magnification

Before cleaning

After cleaning

Data:

First described in Slide Rule Gazette 15, 2014

Questions:

(Rare) product, prototype or home–made?
It has already been cleaned quite considerably to get it open and into the present state it is in – Should it be cleaned further?