It is always best to start with what you know and get your sea legs before tearing off into deeper waters. With this in mind I started with the bottom of the piece: a simple platform with concave sides. Simple in theory except for the fact that if made from solid wood it would be unmovable. So I made a grid pattern to strengthen the inside yet still leave the piece light, know as a torsion box.
sandwiching the torsion box onto the bottom of the base.
I then added 2" of particle board around the edges and routed to match the bottom template.
quite the mess.
I then sandwiched on the top sheet of plywood to complete the box. The end result, while still heavy, is surprisingly light for its mass and is strong as steal.