The cross over section of the legs  need a joint that gives the legs a range of motion that allow them to extend and lock for use but to also be folded when not in use. These are some joint mechanisms along those lines.

The ratchet joint (similar to a knee joint) is one of the suitable types joints similar to the one implemented in the Bambi table by Caroline Olsson.The location and angle of the table legs are adjustable and lockable at different points as seen below.

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