I am starting to make some bunkers and various buildings out of card, but I don't know where to find something like 1mm thick cardboard/cardstock. I know this is a standard size used by modelers and it is usually referenced as "easy to find" by the modeling articles but I don't know where to pick it up at or even what it is called. I tried searching on google but I don't find much.
Where do you guys source your ~1mm card from?
I have a staples near by but I couldn't find anything on their site.