with some testing from a near-uv led I have found that several layers (6+) of the orange celophane giftwrap can significantly reduce the near-uv light that either enters or leaves an enclosure at least as well as the official film, and yes the official film is not able to be considered a structural material as it is just about twice the stiffness of the celophane, so if you want the rigidity of a window then you will want either glass, perspex or polycarbonate sheets.
about the laser windows, as we NEED the 405nm(+/-10%)(my guess at needed tolerances) so 400-410nm for the laser window blocking, there was only three that had ANY degree of block in the 400-450nm range and one(440 model) was only a 2+ factor(the lowest rating of all the rating listed and the higher the rating the better for us as less light of that wavelength will pass through(and 18% visible light transmittance),
the second(425 model) has a 4+ rating (claims to allow 26% of visible light )transmittance,
the third (410 model) also has a 4+ rating and 43% visible light transmittance
the point about light transmittance is it needs brighter lighting behind the window to see through the lower transmittance windows than the higher transmittance windows as the window is BLOCKING all but the % of light