Customized Jupiter-12 35mm F2.8 lens for M42 mount

For sale: Jupiter-12 35mm F2.8. Originally a Contax mount (external bayonet). A custom-made M42 adapter was created to prevent the protruding rear element from interfering with the NEX-7. While it could be mounted with a 4mm E-mount adapter ring, barely avoiding the sensor, infinity focus could not be achieved, so I am reluctantly selling it. It seems to work with the α7 series, even with the E-mount (infinity focus might be possible if the lens were closer to the sensor, but I was afraid of interference with the rear element). Since it's a versatile M42 mount, there's a wide range of possibilities. I don't own one, but it might work with a PENTAX K-7.

*I cannot guarantee focus or infinity focus as I have not been able to confirm it.
Due to the above reasons, there are no sample photos.
Please refer to the examples on Flickr:
https://www.flickr.com/photos/haru__q/23291207215/
https://www.flickr.com/photos/yandho/8957576739/
https://www.flickr.com/photos/kojotisko/15083835411/

★Please be sure to check my profile★

☆Appearance
Few scratches for its age, in good condition.
☆Optics
Slight dust.
The aperture blades show signs of wear. I don't think it's oil.
☆Operation
No problems.
Please enlarge the photos to check.
★Accessories
○Custom-made M42 adapter (red)
○M42 extension tube for rear element protection (photos 11, 12)
*Photos 13 and 14 show an example of it mounted on an NEX7.
*The camera and other equipment are not included in the sale.

*Listed as aE mount for convenience.
*Due to the nature of used items, scratches, signs of use, and the appearance of the optics may vary depending on the individual's subjective view.
*Please understand that this is a used item before purchasing.
*No claims, no returns.
*Only the lens and the custom-made adapter (red) are for sale. The camera and other equipment for photography are not included.
*This is a homemade adapter made by an amateur. It is made of a soft plastic-like material, so please do not remove it.
*I may have overlooked something, but please forgive me as I am an amateur.
Other features: M42 modification, Russian old lens.