That's a pretty neat design. Appeals to my eye.
The "undertop"... if it were "natural-grain solids"... wouldn't be too bad for movement issues if it were attached to the carcase in the center of each side, then allowed to move front & rear. I presume the grain would flow left to right, so all the movement would be front to rear. A single attachment point in the middle of each side would permit that. The top shouldn't be firmly attached to the legs, just allowed to slide on the cross-dado.
OR... if the sides were oriented such that the grain is VERTICAL there, and made also of natural-grain solids, then the sides would move along with the "undertop" and all would be well if the "undertop were completely attached to both the sides and the legs... PROVIDED that the glass & frame TOP were allowed to slip in either the front or rear leg dados.
The curved sides could be made from solids, provided you started with thick stock & built a swing-arm router rig to hollow it. If you did it that way, the inside of the carcase would be angular; only the outside would be curved.
OR... kerf-bent plywood would do it... OR... ordinary 1/4" ply should bend to that radius without kerf cuts... OR... the sides could be built up from veneers, over a form used for both sides to ensure that their curves would be identical.
OR... the sides COULD be built up from vertically-oriented boards, face-laminated into a butcherblock panel after bandsawing to the curve you want. I mean... lay each smallish board flat & cut the curve out of one edge, then cut another just like it, and face-laminate 'em together, then another, and so on till your stack of face-laminated boards is as tall as the sides of the nightstand are WIDE.
OR... one could even build up the sides vertically from small boards of gradually diminishing width, bandsawn at a slight angle; in this case, the sides would have horizontal grain and the "undertop" would need to be slip-mounted but the glass's frame wouldn't.
-- Tim --
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