Cradle bands

An appeal for information. Does anyone out there in interweb-land know anything about cradle bands in Shetland?

Cradle bands were used across a cot in order to stop a child falling out. I know there are examples in Shetland - Unst Heritage Centre has one - but I do not know anything about them. Who made them, and how? What were they made of? Can any readers remember them being used in Shetland? Any help would be very gratefully received.