Where can I find plastic strips or sheets of approx. 1-2mm thick?

I am attempting to make a model of a building in construction. I need the plastic to be hard and color means nothing. I am making the beams and columns for the building.Where can I find plastic strips or sheets of approx. 1-2mm thick?
Did you try IKEAWhere can I find plastic strips or sheets of approx. 1-2mm thick?
Use a plastic coffee container. If you cut the strips vertical, you could ';roll'; them into a column. If you want a square column, cut narrower strips and glue four of them together. If a taller column is needed, you can overlay one on top of the other.
architects routinely build scale models of buildings using foam board. it is simply styro-foam sandwiched between to pieces of poster board. it's approximately 1/4 inch thick and available in 2 foot by 3 foot sheets at most office supply stores, and can be cut easily with a craft knife or razor knife into any shape you want. thickness can be achieved by simply gluing up layers.