A system and method of preparing a metal object for machining, wherein the metal object comprises at least two working portions that are to be machined and that are connected to remote sides or ends of an intermediate portion of the metal object, the method comprising: inserting the intermediate portion into a casting mold, such that the at least two working portions protrude from the casting mold; pouring a liquid metal material into the casting mold so as to cover the intermediate portion; allowing the liquid metal to cool, thereby forming a cast bulk surrounding the intermediate portion of the metal object; and removing the casting mold, whereby the cast bulk enables machining of the at least two working portions to be carried out while the second cast segment is being held.

A method for preparing a micro-nano flexible conductive circuit based on ultrasonic driving of liquid metal comprises the following steps: preparing a mold with a channel pattern and a liquid metal chamber by 3D printing, and adding a well-mixed flexible substrate resin mixture into the mold; then, eliminating bubbles, curing, and stripping from the mold to obtain a bottom-uncovered flexible substrate; covering the bottom of the bottom-uncovered flexible substrate with a base plate to obtain a bottom-covered flexible substrate mold; fixing the bottom-covered flexible substrate mold on a metal fixture table, injecting liquid metal into the liquid metal chamber, allowing an ultrasonic welding machine to come in contact with the fixture table on one side, and applying ultrasound to fill the liquid metal in a channel; and removing the base plate to obtain a liquid metal flexible conductive circuit.