Window guide please and is there anywhere locally I can pickup window molding?

[SnowPunk98]

I bought the plexiglass today and I cant find the molding anywhere and would rather not order it because of the cost of shipping is there anywhere I can pick it up locally im in Orange County, CA also can I get a link to a guide I know you have to cut the plexi and case but I dont know if there needs to be a size differance to account for the molding