This is modeled after the hi-viz patch tht Canadian CF-18 pilots and groundcrew wear.
You can use it to display on your wall, or glue magnets to it to put on your refrigerator. Perhaps use it as a base for your plastic model.
It measures 290mm in diameter and 5mm high, but you can scale it to your needs. Paint it as pictured, with a blue roundel ring, or in low-viz colours if you wish.