I thinking of building a mass loaded platform based on the Cloud 11. I was thinking of sandwiching 4 medicinballs between a bottom plate of wood (a cutting board probably) and a 18 x 24 piece of 1" slate. A turntable will be placed on top of the slate.
I'm close to a slate quarry (I believe the same quarry that supplies OMA) and they can provide me with 1" slabs, honed on all sides for under a hundred bucks.
Is there any advantage of carving the baseplate with large radius cups to allow the balls to roll uphill - similar to a rollerblock?