My first question is why did you not arrange to meet - or schedule something when you spoke together at Hannover?

That would have been easiest. For myself I would send out a questionnaire - in the post because so few people do that these days (you could back it up online if they would prefer to do it that way, so give a link on the covering letter). That way you can find out how interested they really are and how they would like to proceed.

You spoke to loads of people there, you should have a good idea of what people were thinking. That will be a good basis to base the questionnaire on and give it some real meaning to your prospects.

It will act as both sales letter and information gathering instrument.

Dare I say it? The sort of info. you should have gotten at the time?

Moriarty

I would start with a "personalized thank you email" and a promise to follow up by phone in a few days. That sets the stage for your call, and starts the perception that you're the type to achieve what you promise. Don't send a price list (since you don't know what their needs are or when). The goal of your call is to interview them for what they need, and then determine if a visit would be best, or a follow-up interview with their team, etc.

today, before doing anything else, I would send a personal handwritten note using ancient technology called snail mail to thank people for filling out the questionnaire, and include a business card. Let them know you will be in touch.

Please do not send another questionnaire. They already took the time to fill out one. Now you have them fill out another one? And then you will have a salesperson call them and will qualify them a third time? Why don't you just throw water in their face?

After you have sent out thank you cards, you will have a bit of time to analyze your results and plan a strategy to qualify and cultivate and educate your potential partners. I would be more than happy to help (no charge).

By phone, definitely - to establish the beginnings of a "relationship" on which you will then continue to build by following-up on a regular basis depending on the feedback you get - and keep a record of - during those phone conversations. You can certainly offer to provide a price list at any point during those phone conversations, but to mail or email one without first building the relationship is unlikely to produce any sales. People do the selling. Price lists are merely some of the tools they can use.