; Methane (CH4) molecule model ; by Andy Yeh (2014) to arm fd 0.7 rd 90 setscale 0.4 0.5 0.4 setmat 0 32 can ru 90 fd 0.5 rd 90 setmat 0 33 can ru 90 fd 0.7 rd 90 setscale 1 1 1 ball ru 90 bk 1.9 end cs reset setbg 43 make "tetra_angle 2 * arctan sqrt 2 setmat 0 32 ball ru 90 arm repeat 3 [ rd :tetra_angle arm ru :tetra_angle tl 120 ] rd 90 ; back to beginning direction showall