I carefully scalloped out the inside of the top and back using the arbortech woodcarver in my angle grinder, then used a small sureform curved shaper and then a scraper to smooth out the inside.

Then I thinned the boards with the planer thicknesser, taking care to check the thickness between each pass to ensure that it didn’t break through into the concave portion.

I used a forstner bit to cut the two round sound holes and shaped the convex surface with the wasp belt sanding attachment mounted on the drill press. There is still some way to go yet, but the shape is emerging in a fairly satisfactory way – I suspect there will be a couple more evenings of shaping before the top is ready to fit onto the ribs.

But here is the progress so far

And to give an impression of how the whole thing might look when it is complete…