I'm going to install a 2" conduit from my unfinished basement into the attic, through the first and second floor. It will be used primarily for getting Cat6 cables into upstairs bedrooms. 2" diameter is just for future-proofing it.
I know I need to use a fireblocking caulk around the conduit in each penetration through the bottom or top wall plate, but what about the conduit itself? I'm essentially creating a 2" chimney from basement into attic, and the conduit will be only 25% filled initially. How can I create removable "plugs" for that conduit so I can add more cables later?