This sub-forum is pretty low traffic. It might be more productive to move it to the luthiers forum. I mean, I've heard you are a luthier...
As for the questions, as always, it depends on the crowd.
For example, will it be a convention type of event? If it is, expect to see people passing by and watching you for a minute or two before continuing somewhere else; to keep them watching, make it interesting. Wood impact on sound might be a suitable topic. I've been told it's good to have lots of anecdotes when trying to keep someone's attention; like how did you get to the 2 wood body on the Z series.
On the other hand, if it's a reserve-seat type of event, you can expect people who see you to come to see
you. In that case, make it useful and different; bass design for designers is a nice topic in that case.
A new topic idea: a product is useless without being sold. How about talking about pushing a guitar on the market? Meeting players? Working with dealers? Customer service? How to manage an offshore build (like the C bass)? I don't know how much is there to say about this, but it is a vital topic for any luthier trying to make luthiery his/her primary job.
You could ask mods or an admin to move this to the luthiers corner if you want to.