Once you've used the script you'll be able to refer to them while offline and organise your messages by date, sender, title and shoe size and never again worry again that Robot will lose your messages!
While I've tried to make it as easy to use as possible, this does require some installation and setting up of Perl and some modules. It's not really easy, but I've tried to explain how to use it as best I can and a relatively competent computer user should be able to figure out any problems. If you get it right first time it should take you no longer than 10 minutes to set up, and a second or two per message to download them.
The script uses the modules LWP and Mechanize to log in to your instructables account and then fetch web pages and then Perl regular expressions to separate out the useful content. Even if you don't want to download your entire inbox it might prove useful to see how to use Perl to scrape web pages for information.