I expect many revisions to follow. As Sputniks differ from body to body, all dimensions here are approximations only. Please measure your own camera carefully before making baffles or plates. Internal Reflections Probably the silliest of design concepts was having a shiny surface to the inner chambers of the Sputnik. Light reflects off the sides and fogs the image, thereby greatly reducing contrast.
Flocked paper is a fuzzy black material that looks like very fine velvet.
It is available from Edmund Scientific Co. at a very reasonable price. To line the inside, cut out separate pieces for each of the sides as well as top and bottom of the film chambers. Making a paper template first would be helpful. When they fit, glue them in place with contact cement. Baffling involves making walls inside the chambers to block the reflections.