A very interesting work - someone had tried unsuccessfully to make a homemade photosniper lens that mounts an M39 thread mount lens and attaches to a camera like an early Zenit.

I would guess that the reason it was never finished was the incorrect execution of the squeeze-type focusing: when pressed it applies uneven pressure on the sliding PVC pipes that makes it very hard to actually slide in and out.

There is a lens element halfway inside the pipe. The Helios-44 lens was mounted afterward to demonstrate how lens would be attached to the assembly.

Collection of Vladislav Kern