I took the kids and the dog for a walk last night, and made the dog wear the Dog Safety Hat. I also let my son wear the Spy Hat.
While the wearing of the Spy Hat was pretty much an unqualified success, involving a fight between the children regarding whether my daughter should also be allowed to wear the hat, and multiple stops for my son to check the distance to the sidewalk or the distance to a tree, the Dog Safety Hat fared less well.
The original idea for the Dog Safety Hat was to be able to see the LEDs on the dog's back while he was wearing the bandanna, with a secondary use for humans as a fun hat. When we designed it, we used a person as a model rather than a dog (mostly because they're a lot easier to deal with), and subsequently designed it that way.
When walking the dog, we noticed that a lot of the LEDs got caught up in folds of the fabric, or ended up tucked under his collar while he was wearing it. As a result, on average only 2 or 3 of the 12 LEDs were visible most of the time. We decided this is due to the different ways dogs wear bandannas from how people wear them.
When a person wears a bandanna on her head, she generally ties it with the diagonal length across her forehead, and ties the ends behind her head with the tail tucked in. In consequence, for LEDs, the most visible portion of the bandanna is along the center diagonal, which is where we situated most of our LEDs. For a dog, the most visible portion of the bandanna is the tail, laying along the dog's back. We didn't put ANY LEDs here because they're be covered when a person wears the hat. Looking at the picture above, you can see that the hat's actually poorly designed for a dog, as the LEDs only cover the area near his head, while the majority of the visible space has no LEDs.
I guess the takeaway is that by trying to design our hat for multiple users we made it much less useful for the purpose for which it was originally intended.
The good news is that my daughter has a hat she can wear, and we did verify that it works well to help find people in a crowd. It just doesn't work as well as we'd hoped to keep the dog safe.
Now that we know better, we can make an improved version for the dog.