About 10 years ago, I put together this camera from assorted parts and assemblies.
I made some modifications along the way.
These included added light trap seals inside, and an accessory shoe.
Biggest change was to add a second lens mount to the front, to hold 42mm threaded Universal Screwmount lenses, while retaining the original Argus lens threading, concentric within the 42mm mount threads. Thus, camera will function with original Argus lenses, as well as Pentax / Praktica SLR type lenses.
The two mounts are a different registration distance from the film plane, to maintain correct focus characteristics.
To finish it off, I tested the shutter speeds electronically and marked the new values on the dial, and then covered the front with skin cut from a velour-textured material.
Rangefinder had to be left uncoupled, to make room for the new lens mount. But it is still functional as an uncoupled rangefinder, so long as the lens mounted does not block its view.

This morning I loaded the camera with a roll of Walgreens ASA 200 print film, and headed for the Meramec Greenway access area in Valley Park, Missouri.
Three lenses with me were a Japanese m42 screwmount Vivitar f:2.8 / 35mm wide angle with "preset" type aperture rings, a Russian made m42 screwmount Helios f:2 / 58mm "normal" lens with preset aperture rings, and a Japanese made Soligor f:4.5 / 135mm tele, made specifically for Argus C3 bodies.
While shooting my roll of film, I changed between the three lenses frequently. The dual screwmount system allowed for quick and easy changes.
Of the three lenses, I think the Russian lens performed the best.
The Soligor tele lens did flare noticably when pointing in the general direction of the light, showed some exposure vignette when stopped down, and seemed a tad softer in definition than the other two lenses.

Please click on thumbnails to see enlarged.
All images are ©2012 E.J.Kowalski.