I've been wrestling with Seder plate design for probably as long ago as the beginning of my potting life in 1985. I grew up with Passover Seders ("Sedorim" in Hebrew) and know many who, like me, continue to make two Sedorim every year. So this is a natural item for me to try to do well. You can substitute 'conquer' instead of "wrestle", if you want. In any case, if the long years of many unsuccessful tries were a wrestle, I finally feel that I've pinned the sucker to the mat. Suddenly it feels kind of easy.
Here's how I do it. I roll out a very big slab, cut out a large round shape, impress the fresh clay circle here and there with a matzah-patterned texture (I made the latex texture mats myself), and lay the circle into a 20" round shallow form (made of clay by a friend) to help it settle into a gentle curve. Hand drawn designs, red dots for a placement key for 6 small dishes, pass the whole shebang through a couple of kiln fires, and voila! 17" diameter Seder plate with dishes. An overnight success after 30 years.
$140, at my space in The Gallery Downstairs and here on my website on the Jewish Life page.
(Seder Plate, 17" in diameter, handbuilt, wheel-thrown, textured and freely drawn. 2016 Mimi Stadler Pottery)
(Image of what goes in each small dish. For the charoset, I put wording only. Because how do you draw charoset? It looks like chunky mortar. 2016 Mimi Stadler Pottery)
(Matzah-textured 17" Seder plate, color coded for placement of 3.5" small dishes. 2016 Mimi Stadler Pottery)