Welcome to the forum Bob. I have seen blowguns made from river cane and bamboo. I think some are made by splitting a fairly straight branch or thin trunk and gauging a half round channel in each piece then putting it bak together. I think those may be bound with vines or such to hold them. They may even use a natural sap as a glue. I have made glue from pine sap with the lint from dryer filter mixed in. You melt it for use. Found it on a bushcraft forum.