(Original Forum Question : I understand that there are some electronic devices for accurately measuring the mm of seashells. Can anyone refer me to websites of sellers of such equipment ?)
There are plenty of them available on eBay, at quite low prices. I got a nice one on eBay for about $15.00, that measures objects up to 150 mm (6 inches) in .01 mm or .001 inch increments. Go to eBay (www.ebay.com) and search for "electronic digital caliper".
(Answer by M. Paul Monfils via the Forum)