Skye's crate training has been a passive training. We put the crate outside in our covered patio and just waited. Professor rat helped her to go in it at the beginning, and it slowly became one of the places she likes to hangout in.
She often runs in it after a zoomie or an exciting play session. I've seen her in it when it's windy and cannot get in the house. We can now get her in by tossing treats and toys. To increase the duration of her stay inside, we've been giving her toys stuffed with treats. And recently, I've been able to ask her to lay down in it!
How cool is that?!