Preface: I’m not a crafter, so this stuff is new to me.
Polymer clays have the proffered advantage that they can be cured in a home oven. Nice but not a decisive advantage for me as I have access to a school kiln.
I just wonder whether they are durable enough for uses like traditional pottery.
Things like coffee table containers or platters, and outdoor lawn art and sundials.
[ Should this have gone into Café Society?
I had been thinking that was only for spectator arts, but perhaps it’s also for the creative questions? If so, please move for me. Thanks. ]
When polymer clay is cured, the result is a firm slightly flexible plastic. AFAIK, it can only be used for decorative purposes.
The polymer clays are NOT ceramics. The cure/harden in a domestic oven in a relatively short time. Not glass hard but fairly durable. When cured pieces are comparable to a not soft but not real hard plastic. They can be carved, filed, drilled, tapped, etc. One big advantage is the color, like ugly, goes all the way to the bone/center. Colored stock can be blended to obtain non-stock colors and painting is not required. Or you can use a natural base color and acrylic paints to achieve any design or effect desired. It’s fun stuff to work with.
Well, I guess I’ll try some and see what happens when I leave pieces out in the weather. The one nice thing about it is that the color is in from the beginning. Pottery glazes all look dusty grey or pink when applied, and you can be shocked that all your work went into something that comes out a strange color, or colors drip unattractively into each other.
I use polymer clay for bead jewelry. I’m not sure how waterproof you need your finished pots to be, or how strong. I have had beads split on me with remarkably little pressure.
I am not trying to discourage you - the stuff is lots of fun to work with! Let us know how things turn out!
But it also produces the most amazing combinations and effects 
Frustrating when it doesn’t come out how you imagine, but it can be a wonderful surprise.
Polymer clay is quite a bit more expensive than ceramic clay, if I’m not mistaken.
It is, I use Sculpey which is sold in two-ounces sizes for about $1.69 and also in a one pound block for about $12.99.
As for its weather-proofing, the stuff is easily paintable. If you wanted to mix the colors in the clay itself, you could then coat the finished piece with a clear lacquer. Or. if you wanted to do it the easy way, bake, then paint it the color you want using weather-proof paints.