I designed this tray for Wingspan however it would work for many other board games. The second photo shows the tray in use with the Everdell game.

The tray consists of two parts connected in the middle with four 6x2mm magnets. This gives you a couple of options, you can connect both pieces and have a long tray that is the length of a wingspan board or split the tray in half so more players can have trays.

I like to use the tray connected across the back of the board, but other players like to use it split off the side.

The deck box design: https://www.thingiverse.com/thing:4837779