Yes, you can easily spray paint multiple pieces of Ceramic knobs together yet ensure that you have a newspaper below these before starting with the painting process. For beginners, you can use a bonding primer and then lightly spray a coat of paint to cover all the surfaces of the hardware. Then once it dries down, move another coat of paint all around the surface.
For the best results use a solution of ammonia and water to ensure that the same is quite clean and clear. Also, use a fine grit sandpaper to achieve an equally fine surface. Then you can opt to decorate the same using any decorative element and stick it on using an adhesive.