How to get what you want
Just ask.
But will you still get what you want?
It depends on how you ask.
Based on my experience, broadcasting a request to the masses on social media doesn't yield a good response. Maybe it's Facebook's algorithm limiting exposure, or maybe it's the way humans are wired to tune out mass broadcasts.
The lesson? Doing a mass broadcast is not enough.
So how should you do it?
Message your Facebook friends one by one.
When I do that, I often get a positive response.
Sure, it takes a lot of work.
You have to compile a list of people who are warm and know you well enough, and you also have to draft a clear script.
Recently, I messaged 200 people and 40 were interested in the project. It took me quite a while to do it.
I guess there's no shortcut, but it works.