Tyvek-like working surface?

Its standard to use Tyvek tape on the forms that create the edges of a deep pour project. And, I have plenty of it and use it, but it is just 2 inches wide. Is there something similar but wider -- like 24 inches -- to use as a bottom or base layer? I like the see-thru look on most of my projects, but it bugs me to have to sand and polish the bottom.