Abstract: Rotary die cutting apparatus comprising a driven rotary cylinder (10) on which is circumferentially mounted a removable forme (11) having knives (14) projecting radially therefrom. The forme (11) is magnetically retained on the surface of the cylinder (10) by a plurality of longitudinally extending steel bars (15, 16, 17) which locate within grooves (19) in the surface of the cylinder (10), each groove (19) coinciding with a plurality of longitudinally spaced magnets (20) which retain the forme (11) during rotation of the cylinder (10). The grooves (19) and magnets (20) are angularly displaced around the circumference of the cylinder (10) to enable a plurality of forme sections (11) to be mounted thereon according to the length of cut to be performed by the knives (14).