Iv seen this....

putting a photo sensitive strip on a table
in red light
Place any sort of negative I used 16mm
on top and steadily shining a beam of light across the surfaces
throw this into paper developer

and after seconds image comes up (negative)
wash only

we took these out and droped in using cotton buds bleach and developer, solarizing and reversing it. Using colours and scraping lines and letters

Spliced together on small loop and it was great

my problem is that when i asked what this roll of tape was the teachers of this wonderfull class who were French replied "....film stock..."

No go when ya go askin for that anywhere really

Any ideas no?