Can the harness be made from all metal clips? I must have for my service animal has chewed plastic ones

When we raised service dogs for Canine Companions for Independence, we were instructed not to leave Halties/Gentle Leaders, or leashes on the dog if they're out of our sight because they can learn to get them off. Same can be said for chewing. If you have to leave it on, you could get some spray product that discourages any chewing. Better yet, arrange to have sessions where the dog doesn't know you're watching and every time they go to chew squirt them with a mixture of 10 to 1 water and vinegar. It won't hurt them and it's great for discouraging negative behaviors. BUT you have to be 100% consistent andd don't let them see you doing it.

What size for a 60 pound german shepard 6 month old female?

I've owned two of these. My GSD wore a medium at 4 months. Now comfortably in a large by 11 months with room to grow at 80 lbs. Medium won't be too small for you at all but you'll end up in another harness at some point. Good luck!

Is this a good service dog in training vest?

Yes. I have a service dog and this is the vest I use. Works great. I like it because I can actually take the patches off when I want too. this is the only vest I will buy. great quality and easy to take on and off. I hope this helped you. And good luck with your service dog.

I have ordered one of your Harnesses but is it possible to have all the buckles to be metal and be double stiched?

They have a different listing for a version with all 4 metal clips. Look up icefang metal clips x4 harness you should find it. It's also in the suggestions on this listing.