These adapters are not copies of the Amedeo adapters, but as far as I know- these are original designs.
cameraderie.org
Some things I learned: the inner portions of the helical are not painted black. This was a problem with a Zeiss 8.5cm F4 Triotar. Solution was to use a Black marker on the shiny parts, reflections gone. Aligning the outer helical with those on the lens required a little work. With using a Zeiss lens on the inner helical, you might need to adjust the lens slightly. The Pitch of the Helical in the adapter translates the rotation of the Zeiss lens to the 51.6mm standard for the RF of the camera. Amedeo uses an indexed cam for this. This adapter has a straight cam. A Nikon RF 5cm internal mount lens will focus perfectly on it, and a Contax External mount lens focuses perfectly on it.
Leica - Inexpensive Adapter, Nikon RF to Leica Thread Mount. ~$70.
Just arrived in the mail, under $70 with shipping. This compares with adapters costing 3x as much. The Amedeo adapters are works of art, his M-Mount adapter for internal mount Contax RF lenses has an indexed cam to correct the slight difference between the Zeiss 52.4mm focal length and the...

Some things I learned: the inner portions of the helical are not painted black. This was a problem with a Zeiss 8.5cm F4 Triotar. Solution was to use a Black marker on the shiny parts, reflections gone. Aligning the outer helical with those on the lens required a little work. With using a Zeiss lens on the inner helical, you might need to adjust the lens slightly. The Pitch of the Helical in the adapter translates the rotation of the Zeiss lens to the 51.6mm standard for the RF of the camera. Amedeo uses an indexed cam for this. This adapter has a straight cam. A Nikon RF 5cm internal mount lens will focus perfectly on it, and a Contax External mount lens focuses perfectly on it.