has the home brew developer ... you need to make sure your water is alkaline for it to work ..
i haven't scanned some of them
this was done on photo paper that i exposed with room light on to turn it black, then i coated it with liquid emulsion
and exposed it @ asa 1/2 ...
i have some more black paper coated but have been too busy to expose it ...
i think you might have trouble in your leica because you need to expose it for 1/2second f16 bright sun
and maybe your camera can't be forced to be totally manual ? IDK ...
these were done on metal ( the first one in a pentax k1000 )
and glass ( old clunker 4x5 plate cameras ) ...
sorry i can't post more examples i have trouble getting my scans to look like my plates
and have to 'tweek" them more than apug allows so i don't post them ..