Here is easy way to make filled hangings. When using this technique filling is easier. I use here cotton wool sheets to fill the hangings. These are my own designs but anyone is free to get inspired.
Use the felting needle and mat to felt the wool on felt sheet. The outlining of the smaller heart gives you the form to work.
Decorate the hearts in the way you want. I used old recycled buttons and woollen yarn. I edged the felted hears by stem stitches.
You need the background for the hearts. Cut similar sized felt sheet (use the processed one as a pattern) and place it under the heart fabric you have worked with. You don't need to draw the hearts on the back ground felt sheet.
Cut also similar sized cotton wool sheet. (I used two layers of 80g/m2 thick cotton wool.) Place the cotton wool between the felt sheets and fasten all these layers together with pins.
Sew the layers together from the front side by sewing machine. Sew far enough (1cm) from the drawn outlining.
Use good scissors to cut the hearts separate. After separating the hearts cut them more precise so that drawn outlining will be cut off.
You can fasten a yarn to hang the hearts. These hearts are still missing the fastening system because they are going to be a part of a bigger art project.