This is a slight simplification of the original model, without hole, and without the strange behaviour of the upper right bending border, while printing. I redesigned it from scratch. The main difference is that all the surfaces and curves are horizontal. There is not vertical bending of the curve. But the 3d effect remains. With the same elevated borders. I had to rebuild it from its 2d base shade to get this result, after hours trying to change the original model without success.