When our spelling list followed the long /i/ pattern, I typed up the week's words (smiley monster font), copied them onto yellow construction paper, and had kids sort them into the labeled French fry containers (is the long /i/ sound made with "-igh", "i-consonant-e", "y", or some other spelling pattern?) I know I've seen this on the Internet somewhere. The kids thought it was sooo cool.
To get the McDonald's boxes, I walked in and asked for them, simple as that. I felt foolish, but the teenage girl returned my explanation with a smirk and a handful of red boxes for free.