Seems that birdbaths are a big draw. But birdbaths are silly expensive. So... I googled around some more and found this and this.
We were unable to find a 18" saucer but the 16" we did find looks alright. Also we couldn't find deep saucers like those shown in the links but as I'm looking for this to be a birdbath and not just a fountain, I think it'll do.
I've ordered a solar fountain pump off of ebay and it should show this week.
In the meantime ---
Here are the components with spouts filed out with a round bastard file and the hole drilled in the 8" platter.

Per the directions I soaked the pots over an hour (ended being over 2). I did not have a bastard file on hand and tried a rasp bit in my drill. That didn't work, so off to the store again. I had assumed that the soaking would make the filing easier, but no. It is to cut down on chipping at the work site.
It didn't occur to me to put a work glove on my working hand until I worked up a good sized blister on my guiding/pressure finger.
heh
Assembled --

I wasn't keen on leaving them natural. For one thing the pots were different colors and for another... well, I wanted to play and got it in my head to try to make a lapis finish. After googling around a great deal I found this site.
I picked up the materials last night. I'm a little worried about the "water-based gloss varnish". Of the places I checked out I found no "water-based" varnish. I did find varnish for acrylic and for oil. So I made the first of my assumptions that the acrylic varnish is water-based. My second assumption is this: the directions for the faux lapis have a step where paint and varnish are mixed 1:1 .. well, the varnish indicates that is "should not be used as a medium". I'm going to cross my fingers and disregard that directive on the label.
Here is the base coat of gold spray paint --

The additional 4" pot is for a decorative plant that will sit on top of the overturned 4" saucer in the pump tower.
I had thought to apply 2-3 coats on one side before doing the other. I'm glad I didn't because I ran out of gold very shortly after doing the flip sides. Also, the paint can was incorrect about being able to handle the pieces right away. In moving the pots to my deck box I noticed that I'd smudged away the paint in areas when I flipped them to do the other side.
Ehh, I'm trying for a faux finish and natural rocks aren't perfect so I'm not gonna worry about it.
Sill I'm not touching them again for a couple hours to cut down on damage.
Next up, the aquamarine plus black wash. I was able to find that a "wash brush" was both a brush and a technique. But I have found no specifics as to what "aquamarine plus black" means. I'm gonna wing it.
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Well, aquamarine plus black creates a nice denim color. Main problem I had was trying to figure how much paint I needed and I kept underestimating. As a result some wash is a bit different than others. But, at this point, I like the slight color differences.
On to the strips of color and fly specking ---

As can be seen in the big dish, the paint + varnish dries in well under 5 minutes. I came back to smooth the stripes in and they were all dry. Not the effect I originally wanted, but I think it'll be nice under water.
The thing that is really irritating me is that from what I read I did not need primer for terracotta. That is false.
False false false.
I had seen some flaking of the gold early on and thought it wasn't dry. Well, large bits peeled away when I picked up some of the pots. I'm hoping the sealant will stop all of that cause it is really ticking me off.
Next up -- the gold hash marks and gold fly specking.

I read that the acrylic would darken after drying but I didn't realize what it would look like. I'm happier with the large saucer now.
The gold paint that I used didn't blend out nicely with the round brush and for some reason made a significant amount of specks with the toothbrush. Not sure why it would make more than the other paint. I'm hoping its colors will calm down with drying.
Next up, putting a couple coats of UV resistant sealer on all of the pots.
Should have seen this coming. As I said, use a primer.
When putting down the first layer of sealer one pot fell into another and knocked a large paint chip away. When I picked it up to see how bad things were, the paint pulled away where my fingers were. I'm thinking I can touch up those areas. Not sure.
After letting it dry for a half hour, I came out to see if it was dry to the touch. Most of it was but there were a few wet areas (I had problems seeing where the sealant had coated the pot and ended up spraying much to much sealant on). Well, some paint stuck to me. Luckily it was in a hidden area. But based on how the pain is acting, anything that hits it will knock chips away.
I'm really not sure what to do. Strip the paint and start again? I just don't know.
I'm going to let the current coat sit to 8pm and then flip them to do the other side.
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I put three coats of sealant on both sides and then put 3 coats on the parts that chipped away.
Then I mixed gold, aquamarine, black, and gloss varnish for touching up. After doing that I put on three more coats of sealant over the problem spots.
The issue now is that heat from the sun causes the paint to bubble around the chipped areas. It also makes all surfaces sticky enough to pull the paint off.
At this point I think it looks ok. The bubbles are in hidden areas. I'm not sure that I'm liking it because it's nice or because I'm almost done.
Heh.

I don't like what the flash did to that pic, but I don't have a stand up tripod. Ehh
I'll grow some short flowers in the top pot.
I had thought of gluing the tower parts together. But it is looking likely that I'll be doing piecemeal stripping/repainting over time. So no gluing.
Next step is to wait for the pump to come in. Then buy some tubing based on its outflow port's diameter. Lastly, some marine glue.