I'm undertaking an engineering project, and coincidentally met an expert in the field at a school talk. After talking briefly, he took down my email and offered to help with a section on analysis.
He then sent me an email a couple of days later asking what he could do to help.
Now I really regret this, but I have now left replying to this email for over 5 weeks, and am unsure whether this is a completely lost cause.
There is no reason for me leaving it, other than initial laziness, then the inability to think how to reply after the first week or so; it is now just out of hand.
Needless to day I've learned my lesson, but what would be the best way to let him know I'd like his involvement, without coming across as rude, or implying that his help is only now needed?