Rainedave,
sorry I didn't post sooner in response to your question. I didn't realize there were unread questions on this post. I attached some picture to help illustrate my methods to make round wing tips. The scale tool is wonderful

I'm using Version R2.3 LE(23b) and it only Exports as .SUF not .X files. You can Save files as .X and try to open it in another program but I've been unsuccessful using programs like Autocad 2000.