I do a mix of needle felting and machine felting. Machine felting makes a firmer material, is faster, AND fewer finger sticks! I needle felt over wire armatures with yarn, wool and machine felt. I have found that older, "sticky" wool roving, not suitable for hand spinning, is a great underlayer for needle felting. I have not done hand felting in a long time because last time it hurt my wrists.
How to machine felt:
1) spread out a layer of carded roving (or washed, picked, and fluffed wool) on a smooth scrap of synthetic fabric. spray with warm water and dish soap mix.
2) place additional layers of wool and fabric, alternating.
3) roll into a bundle and tie up.
4) Insert into zippered pillow case (to contain any MESS if the wool escapes)
5) Wash on HOT with sneakers.
6) If needed, roll the other way and wash again.
Air dry flat. Any mistakes can be used for stuffing.
Note: I use a Maytag aggitatorless top-loading machine. On the "heavy soil" setting it does a great job.
I get wool, mohair, and wool/silk roving from Halcyon Yarn in Maine, and from The Mannings in PA (check the web for either.) Also check the "spinners and weavers housecleaning pages" on the web.
And, check out the Maryland Sheel and Wool Festival, first weekend in May.
Best regards, sleeplessmommy