The Decoration on the picture is crochet with some leftover acrylic yarn I had (yellow, green, orange and red) and a
3mm crochet hook

The little crochet circle is 8 cm Ø
The crochet heart is 13 x 12 cm

I crochet every piece twice so front and back look the same. In that way you can even hang it in your window or wherever you want to. And it gives a better shape and more stability to the Decoration.
Both (circle and heart) would look very pretty as applications too.