Making your own prefelts is so easy- and opens up so many opportunities for playing with colors, fibers and textures. Try using two or three different colors in layers; using wool for one layer and then another fiber like alpaca or angora for the next; or making nuno prefelt with a layer of wool and a layer of silk fabric. Handpainted rovings make beautiful prefelts, and make efficient use of the roving when layered onto solid wools. Two layers of wool will be fine for prefelts used for surface designs. For more substantial prefelt, use 3-4 layers. It is wonderful to have a collection of these made and ready to chose from, when the urge to felt arises!
Work on a sheet of bubble wrap.
Lay out a thin layer of wool roving. Use your thumbs to pull open the wool shingles. Overlap each row a little to ensure an even layer.
Press down with your sponge, and with your hands; at first pushing down and then using a gentle rubbing motion. Do this over the entire surface.
Remove the sheer. It will lift easily if the wool is wet enough.
After wetting out, you can use the bubble wrap base to even up the edges on on your prefelt. Fold over the bubble wrap, folding the more light, open edges of the fibres over onto the base. Gently surface rub along the fold for 1 minute. This gives you a straight line, and also a more uniform density over the entire felt piece.