I find both City Paper and NEXTpittsburgh do a solid job of highlighting things like that. As to specific events, besides Handmade Arcade, we really love the Westmoreland Arts & Heritage Festival at the end of June.

You just missed Handmade Arcade in the beginning of the month

I'm not sure if craft shows (soap and knick knacks) are what you're actually after, but I Made It markets holds events throughout the year (and today/Saturday)

https://www.imadeitmarket.com/

Or stuff like scale modeling shows

Facebook events tbh, or just googling "conventions in Pittsburgh". There's an oddities convention in January coming to the convention center.

A little bit of everything but usually a nice list: https://festivalguidesandreviews.com/pennsylvania-festivals/

Pm me! My husband has a comic book series and he can talk to you more about conventions and events!

I usually find them through Facebook events