for experimentation purposes, I would go with cardboard and duct tape. just for experimentation purposes though. if you decide to go permanent, then I would look into coroplast or plexi-glass maybe even rubber garden edging.
that seems to be the norm around here. the coroplast is the cheapest since most political signs are made of it. wait a few months and there will be a sea of the stuff in every suburban yard in america.
check out my garaged for a more permanent solution. it may not be the prettiest but it is better than duct tape and cardboard.
Be the change you wish to see in the world