This community is super helpful and helped me with my last post so I have come back for more advice!
For context, I volunteer at a community theatre in the UK. I have expereince with set painting and some experience with set building after helping with touring companies and learning from a family relative who did a degree in stage painting. Sicne then, I first started helping with set building and painting many years ago at this theatre when there was a team of builders who had a solid background in theatre. Unfortunately over the years some of the team has drifted away or have sadly passed away and we have had new people join in with set building but they don't have theatre experience. They are great carpenters and painters but have zero theatre experience.
We have a lot of exisiting flats which are all 12ft tall but vary in width from 1 meter wide to 500cm, 400cm, 300cm wide etc. We have doorway flats and small filler flats. These flats are built as wooden frames covered in 6-8mm plywood and 30+ years of paint. I also know they are fireproofed. Someone on the 'new' team has started to bring in shed loads of thick corrugated plastic sheets that are no bigger than a meter by 50cm. They are complaining about the weight of the existing flats (I have pointed out that nobody should be moving the flats by themselves and they are easily movable with two people) and are suggesting to make new flats using these pieces of corrugated plastic.
While I understand the concerns about the existing flats being heavy, I don't think using several pieces of corrugated plastic is the way forward. When I asked what they would do about the joins, they said they would use duct tape. We often rig lights above the flats to illuminate them in multiple shows. The joins on the corrugated sheets would stick out like a sore thumb. Paint also does not hold very well on the plastic either which the set painters pointed out during the latest production when the actors kept scuffing things. Can the corrugated plastic even be made fire proof??
So, what material would be best for making stage flats that would be durable, paintable and storable?