The realization space is
  [1   0   1    2*x2 - 1   0   1    0    1             2*x2 - 1   2*x2 - 1      2*x2 - 1]
  [0   1   1   x2^2 - x2   0   0    1    1            x2^2 - x2      -x2^2         -x2^2]
  [0   0   0           0   1   1   -1   x1   -2*x2^2 + 3*x2 - 1   2*x2 - 1   2*x2^2 - x2]
in the multivariate polynomial ring in 2 variables over ZZ
avoiding the zero loci of the polynomials
RingElem[x2, x2 - 1, x2^2 + 2*x2 - 1, 2*x2 - 1, x1*x2 + 2*x2 - 1, x1 - x2, x1, 2*x1*x2 - x1 - x2^2 + 3*x2 - 1, x1*x2^2 + x2^2 - 3*x2 + 1, x2^2 - 3*x2 + 1, 2*x1*x2 - x1 + x2^2, x1*x2^2 + 2*x2 - 1, x1 - 1, 2*x1*x2^2 - x1*x2 - x2^2 + 3*x2 - 1, x1 + x2 - 1, x1*x2 - x1 + x2, x1 + 1, x1*x2^2 - x1*x2 - x2^2 + 3*x2 - 1]