Making postcards from felt is a great excuse to try all sorts of felting techniques. You can layer up wool colours, fabric scraps, fibre and printing or stencils to create your postcard picture.
Here is one way to make a 15cm x 10cm felted postcard.
Lay out two layers of wool tops to cover an area approximately 22cm x 15cm. This allows for shrinkage - you should end up with a well felted postcard by the time you have shrunk it down to the final size. Using a plain coloured wool will make a good base to write on the back of the postcard later.
Add coloured wool, fibres and fabric scraps of your choice to build up your postcard 'picture'.
Cover the layout with some netting and wet down with soapy water. A plastic bag or a small piece of bubble wrap can be used on the surface to press the water into the wool.
Blotting the excess water with a towel will make it easy to remove the netting.
Add an optional layer of fine fabric on top. Here a piece of hand painted silk organza has been used. Light weight fabrics made from natural fibres will generally integrate best into the felt.
Wet this down and gently smooth the fabric onto the wool base underneath (use the netting and plastic bag/bubble wrap again).
Begin felting. Start gently and keep going until the felt has shrunk down to 15cm x 10cm. You can trim any uneven edges with scissors if you wish and then felt a bit more to finish the cut edges.
Rinse out the finished felt in clean water to remove the soap and dry the felt flat.
When your postcard is dry you can 'write' the details on the back. This one was done by painting fabric paint thinned with textile medium using a small brush but there are many other options.