Zazzle has the category for pet harnesses (cat and dog harnesses too) but I couldn’t find a single one in the market place. A retired item?
I bought one at Petco for our cat Luna but it’s falling apart already and Petco has a hard time restocking - I already have checked several times to buy a replacement for our feline.
They would be so much fun to design too.
@MOM as far as I know and can recall, Zazzle has not carried pet harnesses before.
you may have stumbled onto an upcoming product before its launch! 
@WHS_Designs Oh, I would love, love, love that. I had suggested it some time ago by email to Zazzle but today, after seeing the post about car window shades I just created a post. I’m crossing my fingers now!! 
Zazzle carried 3 sizes of pet (dog) shirts until they were (sadly) dropped a few years ago. I didn’t sell very many, but they were still nice to design on … plus, the dogs used to model the shirts were so doggone adorable!!
I think car shades would be a great addition, too … and not just for summer!