Yes, you can sit on this. No, the legs won't cave in-- unless you are 500 lbs or so. This table is constructed of cypress, brazilian cherry, spalted poplar, regular poplar, and salvaged heart pine for the legs.
The green chunks down the center are slices from a spalted poplar post retrieved from a lumber yard in Troy, AL. Each piece has a tiny bit missing on one side, so I flip flopped that recessed side. What resulted looked to me like the track for a tractor tire left in the dirt.
44" long, 20" tall, 20" wide.