First, wash the glass jars well in warm, soapy water to give the paint a clean, oil-free surface to adhere to.
Use the masking tape to mark out the middle horizontal line of the jar.
Carefully fill in around this line with small dots in a selection of paint colours. You can go for a regular, or irregular pattern, there's no set rules. Be as creative as you like. I decided to go for a solid line of white dots as a border at the top and bottom.
Then, remove the masking tape and fill in the dots underneath the centre line that you have just filled in.
Leave the paint to dry for 24 hours.
Heat the oven to 150 degrees Celsius and bake the jars (without the lids) for 35 minutes. Leave to cool.
Other ideas: For my second jar I decide to change it around a little. I put the masking tape on the top of the jar and completely filled in the bottom with the same fuchsia colour that I had used for the dots on the first jar. Then I did a single row of white dots above that, and then a single row of white dots around the neck jar.
Why not experiment with different combinations of patterns and colours and let me know how it goes?