Let's make an overview of all materials you need for the bag. First, carded wool, the best fineness is 29-32 micron, 130-160 gramm (4,4-5,6 oz) depending on the size of the bag.
Then, some wool top (fineness 18-19 micron), it will come to the inner part of the bag, 40-50 gramm (1,4-1,7 oz). An assortement of decorative fibers (viscose, rayon, tencel or bamboo).
You will need usial felting and sewing utencils. Svetlana recommends to use an electric sander, but you may also work without it.