I wanted to have my dog to wear a rollei action camera. I found thing:1001901.
I liked it, printed it and it worked, but I had some ideas how to improve it.

First, I wanted to fasten the straps not crossed. Second I liked to add a fast release - and third I thougt a second mount on the chest would be a good idea :)
In my first tries I sewed the straps, which of corse works great, but a much easier way to try different straps (normal and elastic) are the smal buckles I added later.

Print the harness itself, back and chest, standing up, as shown in the picture. You will have to add raft and support.
The female strap buckle also needed support here.

Made for 1 inch (25 mm) strap, I use normal straps around the neck and under the chest. The long strap around the chest is an elastic one. This one tends to slip out of the lock - so I added annother buckle there.

Here is a first little video made with the cam. Deshaked, cause without deshaking, you will get seasick ;)
https://youtu.be/N4cUMCP71E0
And a second one: https://youtu.be/2wxYcElcCgY

Instead of makes - or as an add-on - I´d really love to watch movies you create with "my" thing and some photos of your Dogs too ;)

UPDATE: Added a version back_large.stl. I changed the radius so the plate is less "curved" and so it may fit better on the back of larger dogs.