I use black polythene bin liners pinned to the door frame above with a length of dowel pinned to the lower edge. Can be rolled up, I just tie it at the top with string looped over it. Joins are done with sticky tape up and down, and dowel pinned in the rolling axis. Polythene doesn't wear out, sticky tape needs re-newing every 10 years or so.
Of course as it just rolls down there is light leak. But a polythene curtain on either side of the door frame renders it pretty well light proof; I just don't print in the middle of the day in high summer.