Homax makes a hand operated sprayer that I've used for knock down
texture and popcorn ceiling texture. Works well if the mud/texture is
mixed to the right consistency. It needs to be able to flow "just
right". The description of pancake batter or oatmeal just doesn't cut
it. Some like it thick and some like it runny. If the product doesn't
flow to the sprayer, it needs to be thinner. If the product runs down
the walls or drips from the ceiling, it needs to be thicker.
Experiment. You'll want to try it on a scrap piece anyway.
There is also the hopper style sprayer that attaches to an air
compressor. This is cheaper, assuming you already own an air
compressor. Mud/texture consistency is the same as above. This unit
will let you cover a lot more area for the effort. 20 square feet is
about all I prefer with the hand held unit (the one with a gallon sized
Now that I think about it, mud consistency of store-bought applesauce
is close to what you want.