Wow - very impressive.
Please tell us the process here - do you export from AC3D as STL and then put that in your CNC machine?
When posting attachments, keep the images less than 640x480 and not too big file sizes, otherwise the upload will fail as you discovered.
You can also inline the image - click the mountain/image icon and paste in your image URL. If your webspace may vanish in the future, it's best to attach the image.