Start with a commutative ring R and an ideal M.
Treat R as degree 0 elements. Add a bunch of elements T in degree 1 such that their image under the differential produces M. Now the zeroth degree homology is R/M, but the first homology is a mess. So repeat the process with a bunch of new variables in degree 2. Lather, rinse, repeat.
Eventually you get a supercommutative differential graded ring with homology R/M concentrated in degree 0. This is exactly what you want, after all you want the number of ghosts to be 0, and nothing physical in any nonzero ghost number.
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