Wrap the highlighter with enameled wire for about 15 turns. Then, coils are wound at both ends of the wire to fix the shape.

Then use a utility knife to remove part of the insulation at both ends of the wire. Note that the pro-Qian Duan insulation can be removed for a whole circle, but only half of the insulation at the other end can be removed.

In this step, the coil is placed on two needles with large pinholes. As a wire support.

Lay the battery flat on the table and fix it with plasticine.

Fix the lead bracket and magnet.