I'm not a lawyer but I've dealt with similar matters in the past. Technically the author of the post, but you as the publisher you can be liable for the content specially if you don't publish the original credits.
That sort of idea was most successfully implemented by a company called Quirky.com (https://www.theverge.com/2015/4/24/8488531/quirky-invention-powered-by-quirky). Quirky got a ton of investment and grew very quickly. I had meetings at their office several times, and it was a really fun environme...