Honestly, this is one of those cases where the $1,000 aluminum crates make sense. I know that sounds like a fortune... but look at what he just destroyed. And one emergency vet trip makes $1,000 look like chump change.
Although, I just found this one, and it's $500
http://www.petcratesdirect.com/aluminum-dog-crates.html
But that's neither here nor there since you're having to deal with this now.
http://www.petcratesdirect.com/dog-crat ... ennel.htmlThis style crate has a four point lock on the door - top and sides

I think the rebar method that Katrina told you about is definitely going to work... until he decides to just chew his way out of the plastic. Does his crate have the wire "windows" or the windows that are just holes cut through the walls of the crate? If they are just cut through, I would replace the crate immediately; as soon as he tests those holes he will be out of the crate in an instant.
I would also not crate him with his collar on, because if he makes it half way out of the door and the collar gets stuck he could get hurt. He could get hurt anyway of course, but that would lower the chances.
A lot of people recommend wire crates for escape artists, personally I don't because Ruby shredded her face trying to get out of hers. it ALL depends on your dog (as always!)