I have three Arduino UNO boards laying around, so I thought it wouldn't have hurt to try making one more efficient and use it in a project. Two of them were gifted to me, so I didn't decide the boards (I usually would go for Nanos). I didn't even touch them, as having one board for developement is already enough, and I thought it was a shame I couldn't find any use for the other two.
That said, custom PCBs are actually a great idea!