I’ve just found a project for the winter!
I’ve been spending hours cleaning seeds from our Szechuan pepper tree (you want the pink husks and not the gritty seeds). I searched online and came across a home-made seed cleaner which I eventually traced back to the UK-based Real Seed company.
Basically, it uses your vacuum cleaner to create an air current which separates the seeds from the chaff. The design is open source which allows you to make one for yourself but have to credit them. You can watch it working on YouTube.