There are so many ways to start a flat needle felted piece, how do you build up your pieces and what wool do you use/prefer?
--- I usually make needle felted prefelt of coarse wool, and go on with merino tops l as I find that the coarser wool helps the merino tops to felt in addition to allow more hues to occur in the finished piece. During the fauvism inspired piece I discovered that I actually quite like how BFL wool behaves and that fewer of the holes left by the needle were showing compared to merino tops - a big plus! That was an eye opener to me, and makes me curious as of how others start and build up their flat needle felted pieces.
I never really needled flat pieces but when doing sculpture yes using a courser like the domestic 56 (RH Lyndsey) or English 56(world of wool)and then covering it in dyed merino. Dyed coriedale was nice for small pieces.
I've used Merino when doing 'pictures', but mostly use something more texturey like drumcarded Merino and coarser wools I've had dyed. Then I add background colours and 'detail' mostly in Merino, or similar blend depending what it is. I've used other bases like felted jumpers, blankets and craft felt too.