You can knit from any yarn you like and your favorite crochet. You can use any yarn-cotton, acrylic, wool. The size of the panel will depend only on the thickness of the yarn - the larger it is -the larger the size of the hanging wall decoration
The sample used yarn cotton 50%- acrylic 50% good twist-361 yds330m / 100gr- red 4 yards , white - 15 yards, melange 230 yards, light blue -260 yards When using sample yarn, the hanging decor was 12 inches wide, 20 inches high.