For example a large cell of {TAIL ~ each primary color} and {HEAD ~ black} can be placed in the four corners 
For example a large cell of { TAIL ~ each primary color } and { HEAD ~ black } can be placed in the four corners
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH