Gill-That British Woman you were asking about details. There are numerous church groups making these bags you would have to find one in your area. The site I found was www.nbbc.ca, it is a church in Burlington, Ontario. If you go to the site, click on Milk Bag Project, on that page click on "info sheet FAQ and instructions" and it will take you to a pdf file which shows you how to make them.
Hope this answers your question.