We had a fascinating talk from Francis Lewis on how to make polymer buttons. There are four brands she uses: Fio, Sculpey, Premo and Kato and each come in a block, which Francis then cuts into slices, before laying them together and rolling them like pastry.
She then uses a pasta machine to assist the rolling. Different colours can be blended at this stage. She repeats folding and rolling until the correct thickness is achieved. Then she rolls them up as evenly as possible making sure there are no air bubbles. This gives you a cane which you then roll to the length you require.
You can the carefully take a number of these canes and mold them together to form a triangle. Then taking several if these triangle slices you can form the button you require.
Francis uses a dedicated convection oven to bake the clay as it does have an unfortunate smell while baking.
Remember to put the holes in your button before baking.