hey check out this link and let me know what you think. i was told he can make for 24" x 72" , also i would ask he put two 4" fan holes one on each side
http://cgi.ebay.com/18-x-72-x-15-Oa...0755QQtcZphotoQQcmdZViewItem#ebayphotohosting
http://cgi.ebay.com/18-x-72-x-15-Oa...0755QQtcZphotoQQcmdZViewItem#ebayphotohosting