Any "Proven" Chicken Tractors For 12 Layers?

[Uncle Marc]

We have a permanent coop. We are getting 12 new chicks today. I will be trying to introduce them to our flock in about 10 weeks. Once they are big enough to be outside I want to put them in a chicken tractor and move them around to let the old hens get to know them a bit.

I hope to have them roosting with our regular layers by 16 weeks.

Any proven tractor plans that will hold a dozen chickens?

Also, any ideas on how to get them into the old coop and let them know it is home, without a murder or two?

Thanks.