RE: How can I make splayed side for a round tray?

Hi Brian
If I understand right what you want to is to put a 45-degree angle all the way around a round tray. If that’s what you want to do ? I would do it on a router table with a “V” shaped jig (see link) and a 45-degree router bit.

https://www.woodsmith.com/article/circular-router-guide/