Buy circular pieces of wood around 10cm diameter (can be found on amazon).
Undercoat each coaster with white water-based paint. Paint both sides and the edges.
Use a glass or compass to draw out the inner circle of the watermelon.
Paint the inner circle a pale pink colour using water-based paint.
Use a larger glass or compass to draw out the outer circle of the watermelon.
Paint the outside of the watermelon with a medium green colour.
Paint over the white between the pink and the green if any colour has gone over the lines.
Use a pencil or create a stencil for the watermelon pips. Place them wherever you wish or follow the pattern below!
Paint the pips in a dark grey or use a pen for more accuracy.
Use a gloss or PVA paint to paint over the watermelon print so it becomes waterproof.