Norton Vinyl Stencil which can be applied to the rear of the Seat. Once adhered, you can use fabric paint and a brush to paint it on. Spray paint may work as well but best to test.
Dimensions of Design are: 120x43mm
Dimensions of the Stencil in total are: 138x58mm
If seat covering is PVC, a multi surface water based paint should work, needless to say the stencil has to be removed when the paint is just touch dry but still soft.