the support for the top could be a knock down setup, kinda like a torsion box build and the top like others have said could be in sections and the sections could be veneered to get the artsy look like you are good at already shaz.. the hinge idea sounds good perhaps the drop leave style setup but in any form you would want it to be light weight to a degree so as to warrant it to be moved for the billards.. if its to much hassel to move, it wont be moved! one way or the other..
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