Build an ASCII Fibonacci Clock
Python 2, 194 182 bytes

from random import*
h=m=H,M=input()
while[h,m]!=[H,M/5]:
 h=m=0;s=[]
 for n in 1,1,2,3,5:c=randint(0,3);h+=c%2*n;m+=c/2*n;s=zip(*(["WRGB"[c]*n]*n+s)[::-1])
for L in s:print"".join(L)


The algorithm is just rejection sampling, so it keeps generating clocks until it gets one that's right. The clock is built by starting with nothing, then doing "add a square above and rotate clockwise" 5 times.

Takes two comma-separated integers via STDIN.

&gt;&gt;&gt; ================================ RESTART ================================
&gt;&gt;&gt; 
7,17
BBBWWWWW
BBRWWWWW
RRRWWWWW
RRRWWWWW
RRRWWWWW
&gt;&gt;&gt; ================================ RESTART ================================
&gt;&gt;&gt; 
7,17
GGBRRRRR
GGRRRRRR
WWWRRRRR
WWWRRRRR
WWWRRRRR