I have nafa patterns..basswood is the main wood used for stretchers,I don't know why.Cedar is a little harder and prone to split..I can't imagine pushing pins into cedar boards for very long at a time.I can split out enough cedar to make a couple mink boards and find out for myself how hard the pushpins are to use.ETA On second thought,it wouldn't make much difference what size the basswood was,I could use the thicker stuff for carving.Buckeye would be good,too.