How to line a crew neck with a Gavroche (pocket square scarf) using magnetic circular discs in diameter of 15mm and a thickness of 2mm. They need to be the right strength and have completely smooth surfaces. They need to be powerful enough to secure the scarf safely, and yet have to remain manageable. The best magnets I have found are the Circular Disc Magnets by E Magnets UK. They come in a huge variety of diameters and thicknesses.