You can use glass cups, dishes, vases or mirrors, depending on their daily use or just a piece of décor, if they are for the daily use, then you have to use certain materials that withstand heat and exposure to water, either if they are for decoration, then there is no need for custom materials that can be replaced by regular materials.
Decoupage on glass is a method that does not need as much effort as other methods, because it is a smooth surface.
Two methods are either on the surface of the cup or the dish from the outside or from the inside, which is the most common method.
The steps of decoupage on the glass if the piece decoration at first wipe the glass using alcohol or wash it with water and dishes soap, then let it dry.
Cut and shape the picture, then glue it either on the outside or inside the surface, it’s up to you, let it dry.
After finishing, grease the glass with a layer of varnish and then let it dry, then grease it again with varnish.
If the piece is for daily use, then in this case, clean the surface, then glue the picture on the façade using decoupage glue, let it dry for at least two days and then put it in the oven for 40 minutes in a temperature of 130°C.