CSBS poster printing requires reading and filling out this web page form:
Instructions are then given back via e-mail.
NOTE: in any one hour, only 7 standard 4x3 foot posters can be printed. That means, if say 30 students all wait to print at 4pm on the 8th, with the lab closing at 5pm on Fridays, 23 of them will end up being quite disappointed.
So, if you want to print for free, instead of going over to CopyWorks Friday evening or Saturday morning and paying $90, you need to get your posters completely done and ready for printing as soon as possible.