startshape x4x
tile {s 54}
rule R {SQUARE{}2*{f 45}R{s.6 1r-90x 2y 1}}
rule x4x {
2 * {s .5 x 9 y 9 b .2} {4*{r 90 x 36} R {} SQUARE {s 17.2 x 18 y 18 b .6 z -1}} 2 * {s .5 x -4.5 y -4.5 z 1 b 1} SQUARE {s 16.7 x -9 y -9 z -1 b .5}
}
startshape x4x
tile {s 54}
rule R {SQUARE{}2*{f 45}R{s.6 1r-90x 2y 1}}
rule x4x {
2 * {s .5 x 9 y 9 b .2} {4*{r 90 x 36} R {} SQUARE {s 17.2 x 18 y 18 b .6 z -1}} 2 * {s .5 x -4.5 y -4.5 z 1 b 1} SQUARE {s 16.7 x -9 y -9 z -1 b .5}
}