JavaScript, 66 64 61 chars
Heavily inspired by TwoScoopsofPig (PHP) and Joe Tuskan (JS).
for(a=[s=0];s!=72;)for(s=i=0;i<18;s+=a[i++]=Math.random()*3+3|0);a
for(a=[s=0];s!=72;)for(s=i=0;i<18;s+=a[i++]=Math.random()*3+3|0);a
for(a=[s=0];s-72;)for(s=i=0;i<18;s+=a[i++]=Math.random()*3+3|0)a
for(a=[s=0];s-72;)for(s=i=0;i<18;s+=a[i++]=Math.random()*3+3|0)a
for(a=s=[];s;)for(i=18,s=72;i;s-=a[--i]=Math.random()*3+3|0)a
for(a=s=[];s;)for(i=18,s=72;i;s-=a[--i]=Math.random()*3+3|0)a