when I build building for 1/100 or 1/144 dio I usually use the products called "Hard rock?"
It's basically the thin plastic plate with the foam core in between. You can get this in various thickness and you can treat it like thick cardboard but you can glue and paint using modelling paints...
Of coz for 1/32 there are numerous resin kits available from 3rd party and if you really want the old Airfix made several in 1/32 scales as well some other major brands...
people living in glass colonies shouldn't throw nuclear stones.