Good tutorial....... You don't need $22 dollars though. Atomic makes Carbon Fiber Arm stiffeners, extactly like what you made. They are on most of the sites and are usually only around $6.00 and they looks awsome.... I have 2 sets of them. Heres a link.
http://cgi.ebay.com/Kyosho-Mini-Z-SS...QQcmdZViewItem