As per Eileen's request :)
The buttons were made from polymer clay. Many brands in the market available namely Super Scupley, Premo Sculpey and Fimo.
1. Cut a piece of clay from the block, condition it i.e. roll it, fold it, squish it, till it's pliable like dough.
2. Do this on a ceramic tile, so no lint will gather on the clay.
3. If you want marbled buttons like I did, work No 1 & 2 in another colour.
4. Roll each colour into logs.
5. Twist both the colours around each other.
6. Fold, roll into a log, fold again, etc until the desired effect is reached.
7. Do not work No 6 too much as the colours will merge and will pass the marbled stage.
8. Finally roll into a log and use a ruler to measure even sized pieces and slice with a sharp blade.
9. Roll the clay between your palms, this should produce an almost perfect round bead.
10. Lay the clay onto a piece of tile and press them down with your finger, it will spread.
11. Use a needle/sharp object and make 2 button holes, ensure the needle touches the tile
12. Work Nos 9-11 until log is finished.
13. Bake in convectional oven, on 150 deg C for 20 mins. DO NOT MICROWAVE.
14. Let it cool and remove from tile.
15. You might need to poke the buttons again to ensure there is a hole big enough for threading.
Good reference is Polymer Clay Central, loaded with tutorials and much more.