The realization space is
  [1   1   0                  x1 - 1   0   1   1         0                  x1 - 1         1    1]
  [0   1   1   2*x1^2 + x1*x2 - 2*x1   0   0   1        x1   2*x1^2 + x1*x2 - 2*x1        x1   x1]
  [0   0   0                       0   1   1   1   -x1 + 1        -x1^2 + 2*x1 - 1   -x1 + 1   x2]
in the multivariate polynomial ring in 2 variables over ZZ
avoiding the zero loci of the polynomials
RingElem[x1 + x2 - 1, x1, x1 - 1, x1^2 + x1*x2 - 2*x1 + 1, x1 + x2 - 2, x1^2 + x1*x2 - 3*x1 + 1, x1 - x2, x2 - 1, 2*x1^2*x2 - x1^2 + x1*x2^2 - 4*x1*x2 + x1 + x2, 2*x1*x2 - x1 + x2^2 - 3*x2 + 1, x2, 2*x1 + x2 - 2, 2*x1^2 + x1*x2 - 3*x1 + 1, 2*x1 - 1, 2*x1^3 + x1^2*x2 - 4*x1^2 + 3*x1 - 1, 3*x1^2 + x1*x2 - 4*x1 + 1, 2*x1^2 + x1*x2 - 4*x1 + 1, 2*x1 + x2 - 3]