This pistol is pictured and described on pages 80 and 81 of "Walther Volume III 1908-1980, by Rankin. There he notes “The Sheetmetal MP was a single shot concealed hammer pistol”.
Rankin feels that although the pistol is a sheetmetal design it was actually manufactured in the mid 30's time frame at the same time the Walther factory was experimenting with producing the Model MP concealed hammer pistol. He is of the opinion, that it was an engineering effort by the factory to determine if these pistols could be produced on a low-cost basis using a mostly all sheetmetal design. This effort would later pay dividends in the late days of WWII.
The pistol is one of the first stepping stones towards the P-38 and a unique example of complex Walther ingenuity and manufacturing expertise.