LOL! It seems I misunderstood "slip". Slip connections won't fit into each other, but they do fit into pipes. That helps. And it means I don't have to worry about "hubs"!
But still, I went back to Home Depot and Lowe's and they just don't have complete selections in any size. I am going to a plumbing specialist store tomorrow. The Home Depot Plumbing Manager suggested one locally. I certainly didn't know about the place.
The local HD and Lowe's have basic parts and I wrote down the prices of the parts they do stock (and to indicate what parts they stock). But I'll be fair about it, if the specialty plumbing store offers competitive prices (within 10% of the HD and Lowe's cost) for the basic parts, I will reward them for the selection by buying all parts there.
Wow, this project is taking so much more time for the design and supply, it is weird. I normally work in wood, so the design is the hard part and the supplies are easy!
I can't wait to get this one done because the parts are so annoying to obtain!