makehole[{{x0_, y0_}, {x1_, y1_}, {x2_, y2_}}] :=
  With[
   {
    x3 = x0 + (x2 - x1),
    y3 = y0,
    pop = (x2 - x1)/3,
    pob = (y0 - y1)/3,
    xpom =
     Sqrt[(Sqrt[(x0 - x1)^2 + (y0 - y1)^2]/3)^2 - ((y0 - y1)/3)^2]
    },
   {
    {{x1 + xpom, y1 + pob}, {x1, y1}, {x1 + pop,
      y1}, {x1 + pop + xpom, y1 + pob}},
    {{x0 - xpom, y0 - pob}, {x1 + xpom, y1 + pob}, {x1 + pop + xpom,
      y1 + pob}, {x0 + pop - xpom, y0 - pob}},
    {{x0, y0}, {x0 - xpom, y0 - pob}, {x0 + pop - xpom,
      y0 - pob}, {x0 + pop, y0}},
    {{x1 + pop + xpom, y1 + pob}, {x1 + pop, y1}, {x2 - pop,
      y2}, {x2 - pop + xpom, y2 + pob}},
    {{x0 + pop, y0}, {x0 + pop - xpom, y0 - pob}, {x3 - pop - xpom,
      y3 - pob}, {x3 - pop, y3}},
    {{x2 - pop + xpom, y2 + pob}, {x2 - pop, y2}, {x2,
      y2}, {x2 + xpom, y2 + pob}},
    {{x3 - pop - xpom, y3 - pob}, {x2 - pop + xpom,
      y2 + pob}, {x2 + xpom, y2 + pob}, {x3 - xpom, y3 - pob}},
    {{x3 - pop, y3}, {x3 - pop - xpom, y3 - pob}, {x3 - xpom,
      y3 - pob}, {x3, y3}}
    }
   ];
Show[GraphicsGrid[
  Partition[
   Map[Graphics[#] &,
    Apply[Polygon,
     Rest@NestList[
       Flatten[Map[makehole, #], 0] &, {{{2, 5}, {1, 2}, {5, 2}}},
       3], {2}]], 1]]]