The thickness itself isn't a problem, but when you've got a thick wad of clay, there's more of a risk for air bubbles in the clay. When you fire clay (this one's going up to somewhere around 2000 degrees before it's done), if there's any air inside it, it will expand and it will escape--even if that means blowing up the piece. (This is why in hollow pieces you will always find at least a little pinhole to let the air out.)
If I had just rolled out this clay to 3/4" inches, it probably would have air bubbles, but this was rolled out to 1/2", most of it cut out, and the thicker parts carefully built up, so it should be alright (I'm telling myself). I mean, I pretty much know what I'm doing. But usually, even when I'm careful like this, I do carve out the thick parts from the back:
Tile made from slab rolled out to prolly 1/4", built up.
Thick parts carved out. So it's really about the same thickness everywhere, for the most part. This one also is carved in such a way you can hang it from a nail.
I did not do this with the Laugh-Out-Loud Cats tile because I was so scared to pick it up too much and mess with it. It's the most complicated bit of sculpting I've ever done*. This is the back of the Laugh-Out-Loud Cats tile:
The white stuff is just dust. The bumps are from pressing a tool in to make the impressions of windows in the buildings. The center is kinda rubbed smooth from working it so much on the other side. It's kind of an ugly little thing, ain't it?
By the way, it will have a finish pretty similar to the elephant tile depicted.
*Besides something like this: