For us, it started on OpenWRT blogs, scouring Alibaba and seeing who got back to us. Later it was email lists and the network of our accelerator. If I was goin

For us, it started on OpenWRT blogs, scouring Alibaba and seeing who got back to us. Later it was email lists and the network of our accelerator. If I was going to custom design, i'd be going to maker meetups in your city, or applying to something like Hxlr8. There are also supplier/customer places that do matchmaking with additional services for a fee (HWTrek for example). I didn't use any. Also, if you can find a Kickstarter of someone who did something at all related, ask who they used. Lots of creators are very happy to tell you!