1
Line a baking sheet with a sheet of wax paper. Arrange the Mason jars upside-down on the baking sheet. Leave enough room between the glasses so you can paint them while they are on the sheet.
2
Scoop a pea-sized dollop of glass paint out of the jar with your paintbrush. Put the paint in the bowl. Add two drops of paint thinner to the bowl. Blend the components with the paintbrush. Scrape the brush against the rim of the bowl to remove the paint.
3
Dip the tip of the paintbrush into the paint. You need only minimal paint to coat the glass.
4
Paint across the bottom of the glass in smooth strokes from one side to the other without stopping. Brush the paint in a thin, transparent layer. The paint may look slightly cloudy as you apply it, but you should still be able to see through it.
5
Paint down the side of the glass in broad, continuous strokes from the one end to the other. Continue painting the glass in straight lines until the glass is coated entirely. Repeat the process to paint the rest of the glasses.
6
Allow the glasses to dry for 12 hours.
7
Draw other embellishments with enamel paint markers to finish decorating the glasses. Print the names of guests or the date of the event for which you are making the glasses. Sketch simple illustrations that are related to your event or are seasonally appropriate. For example, draw bells and flowers for wedding glasses, or fireworks for a Fourth of July barbecue.
8
Return the glasses to the tray, positioned upside-down. Allow the glassess to dry for 12 hours.
9
Place the tray in the oven after the painted decorations dry. Set the oven to 375 degrees Fahrenheit. Bake the glasses for 45 minutes, which sets the paint so that it does not wash off. Turn off the oven and let the glasses cool in the closed oven until they reach room temperature. The glasses should be crystal clear and ready for use after they cool.