Honeycomb lawn plates for seeding surfaces have honeycombed chambers open at the top and hexagonal in cross-section. So that peripheral chamber walls do not really contact one another, peripherally open chambers are provided on the plate edges, the cross-section of which is less than the cross-section...http://www.google.sh/patents/US5689912?utm_source=gb-gplus-sharePatent US5689912 - Honeycomb plate for lawns
