Instead of plastic (and or course NOT glass, duh!) I suppose you could use an old cocktail shaker. That would make a very musical sound.
Originally I had intended to use some large fender washers as the weights, but 'someone' was using those as fabric/pattern weights; needing to improvise the first things that came to hand were the sockets and some quarters.
After shaking, I dump the whole mess into a colander and then into a strainer to remove most of the 'junk'. Repeat the process about 3 times until no more seeds appear. Later, I dump the contents of the colander in an unused part of the yard to allow any stray seeds a chance to grow.
