I would google ridout plastic's in california and pose that question to them, their is a very thin liquid that you squirt on the egdes and it melts the seems or edges together. I just can't remember it's name. but they sell everything you need or could want. they use it in makes large signs. actually here is their info I googled it for ya. hope this helps ya
www.ePlastics.comWe are located at 5535 Ruffin Rd. in San Diego, California 92123
phone 858.560.1551
fax 858.560.1941
Toll Free 1-800-474-3688