I am pretty sure that I'm very likely the only guy within 20 miles or more who makes, buys, and shoots slingshots. It's not something I talk about too much, because people simply do not relate to what modern slingshots are capable of in terms of power and accuracy, and tend to look a bit confused.
The classic image of a kid doing mischief still seems to linger, and adults using a slingshot is viewed as something a shade eccentric. People into shooting sports will tend to go for firearms or archery in Switzerland, and many are members of shooting clubs. Gathering interest for slingshots is an uphill struggle in this context. In contrast, Italy and Spain have a thriving slingshot shooting community that meets for competitions, but these seem to be the only European countries where this is the case (not quite sure why) - maybe the UK should be included. Slingshot shooting is extremely popular in China, though.
Ultimately, slingshot making and shooting does appear to be a rather solitary activity. There is no international federation like in Archery to promote our sport with an emphasis on competitive shooting. My feeling is that one needs to develop the interest among the younger generations, ideally as part of the sports curriculum at schools (good luck with the prevailing political correctness). Organizing open days for the general public to see the performance of top slingshot shooters, and an opportunity to try it out themselves, might be another viable approach: this may involve reaching out to companies supportive of shooting sports to get sponsorship. It has to go beyond a one man show, that's for sure.
My 2 cents worth...