Cylindrical hopper- The basic idea for the cylindrical hopper (starting in covered_hopper17) has been around for a while, e.g., http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1523917 http://www.brickshelf.com/cgi-bin/gallery.cgi?f=33133 My main innovation is using panels on the end to make the space more open, see covered_hopper21 for this detail.