I googled "sled dog harness pattern" and found the following site. Looking at the pictures, I think you could probably buy a harness at the pet store and adapt it to your desired use.

Here is a link that might be useful: Sketchs of dog harness

Try this link. Then go to Buckram Frames, you will find frames for a half skull hat and the pill box.
Theatre House ships quickly and I have all ways been satisfied with anything I've bought thru them.
Kathy G in MI

Here is a link that might be useful: Hat frames

Back when pillbox hats were popular, ala Jackie Kennedy, we simply took belt backing, cut it the desired length, joined the ends to make the circle, then cut a circle of fabric for the top of the hat, interfaced it, covered the sides, and had a pillbox to match our outfits. They're quite easy to make.
Jackie was so stylish!