I would think the same equipment could be used for mud plaster as for shotcrete/gunite etc. There's usually chopped
straw in the mud plaster which might clog the gun though. If you put stucco mesh up, the straw might not be needed or could at least be chopped very short. You could attach tie wires to the barbed wire between the bags and leave them sticking out to tie the stucco mesh to. Poultry netting has also been used in place of stucco mesh. Cheaper I think.
Or you could hire a bunch of kids for a weekend or two to make and throw mud.
Something as rigid and unbreathable as concrete might not be very compatible with earth filled bags. The moisture would never be able to come out of the earthbags so it would never get as strong as it's supposed to be. The curing of the walls can take a very long time depending on climate and sealing them up would prevent it.
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If I am only for myself, what am I?
If not now, when?