Thanks for the shout out, Aaarvark. My name is actually Des Byrne but because everyone gets it wrong... So yes I'm accessible as info@friendsofmaud.org.uk by email.
The pdf prints use similar techniques to other download sites, print on 160 or 200gsm paper and glue to 1mm mount board.
I have devised a way to create transparent windows using masking tape for the frames on acetate film. These can then be painted with a fine brush and steady hand helped by a magnifier or goggles. I stick tape onto film and then cut 1mm wide slices using a guillotine, but scissors can be used too. This then is peeled off the film and used to form the frames.
Here's a GNSR "Verandah" waiting room test piece with the trial windows out front. Inside are the alternative printed windows with acetate in front of them.