No the weather is fine for all the paper, card and smurfs etc its just the homemade clay the damp gets two just the slightest bit of moister and they flop. I still havent found a cheaper beter solution for that yet.
The ground is polostireen and daz modeling clay and thats fine. My castle is made from wall paster and daz and thats been down in a damp garage for a couple of years and has held up fine. apart from it getting boke were things were moved around in there but ive got that back now fixed it up re painted it and its all better.
Funny you mention wallace and gromit years ago I built the wallaces house garden basment and the rocket and all the characters too and even animated them. Took me a couple of years building everything. I even used to make my own characters based on wallace and gromit and used to sell them. But that was years ago and when my parents cleared out there loft it all got frown away. Oh id love to work for Ardman on the wallace and gromit stuff and yes my own smurf design studio would be super lol.
Smurfy regards
Steve