It really isn't so difficult to create such a colony. Take one strong colony with prolific one having 10 frames of brood. Add a body full of emerging brood on top above and excluder. 10 days later, separate as I said, and give graft. 10 days later harvest cells, and do it again. 10 days later...this is what you have. Probably upwards of 15 frames of brood below the excluder...7 or 8 of those open nurses?