looks a bit like the "thinner of the two" sign magnetic panel on a roll you can buy.
you could call anchor magnets or bisbell magnets… think its about £5 a metre x 24inch wide.as kev says, i would have thought laser cut would be best. i have cut stencils from my magnetic roll using our cnc router but no use for small intricate stuff like that as the movement motion of the router shifts the panel from the vacuum bed.