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