Use scraps to offset the straight edge allowing you to cut each edge of the dado with opposite edges of a router bit
Make a pattern using elliptical sticks, and then use a router with flush-cut bit to replicate onto the big stock
Use tape to clamp and only glue where you have to.
Which method is better—by hand or machine?
All you need to build this table is biscuits, bowties, Festools, and straight edges...
"Seventh-grade shop was probably the most fun I had in all my school days. That was kind of the beginning of my woodworking career. Here I am, decades later, still sort of in seventh-grade shop."
Hey Samurai, Aren't you afraid of expansion and contraction? Samurai: "No, I am not afraid of expansion and contraction, and here's why..."
Nice boxes, no-shift
Composite decking machines smoothly, joins well, and resists weather with the best of 'em.