I believe Sgt Peter was also looking for these.
A possible source for new empty metal ointment tubes is herehttp://fagron.us/
They serve compounding pharmacies, where medications are made up on doctor's orders. I dont think you will need a DEA number or anything like that to purchase just empty tubes. If they will not sell to you, you might ask your local pharmacist, especialy a compounding pharmacist, to help you.
Also on a seperate note, cotton 3 strand twist rope (like on shelter halfs and wall tent door flaps) is getting hard to find, but is available by the foot here:http://www.knotandrope.com/store/pc/home.asp