I've been building my wings using strictly a light duty staple gun with 5/16 light duty staples. I am stapling to the ruler spar and us a strip of 3/16 x 1/2 spruce to staple to on the trailing edge. Of course all my wings are bult with 2mm corro.Since I quit using glue I have yet to come out with a less then perfectly straight wing. That little hunk of spuce weight is worth a good wing to me. Tough to beat a derelict when it has a straight wing! I've taken a few pretty hard mid-air and I am still flying staple wings. Their holding up just as good as all the glue wings I've been fighting