The realization space is
  [1   1   x1 - x2 - 1   0   0   1         1         x1 - x2 - 1    0    1    1]
  [1   0     x1 - 2*x2   1   0   1         0           x1 - 2*x2   x1   x1   x1]
  [0   0             0   0   1   1   x1 - x2   x1*x2 - x2^2 - x2   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, x1 - 2, x2, x1 - 2*x2, x2 - 1, x1^2 - x1*x2 - x1 + 2*x2, x1^3 - 2*x1^2*x2 - 2*x1^2 + x1*x2^2 + 5*x1*x2 - 4*x2^2, x1^2 - x1*x2 - 2*x1 - x2^2 + 3*x2, x1^2 - x1*x2 + x2, x1^3 - 2*x1^2*x2 - x1^2 + x1*x2^2 + 2*x1*x2 - 2*x2^2, x1*x2 - x2 - 1, x1^2 - x1*x2 - x1 + x2 - 1, x1^2 - x1*x2 - x1 - x2^2 + x2, x1 - x2 - 1]