Yeah… PLace57 is right. It’s too thick. But that’s a minor problem compared to the rest.
From experience, I can say that such a design will be rejected by Shapeways if you want to print it in metal (gold or silver). Too fragile too handle when it will come out of the “oven”. And if you want to print it in stainless steel, it’s too thin… unless you’re going gangsta rapper and that pendant is a big as your palm. That little bit floating inside the loop of the “L” at the bottom left is another problem.
In short, the hollow “L” is the problem. To make it printable, I’d fill it and make a concave surface to give the idea of the hole. (If you see what I mean.)
Now, to make it nice and smooth like the Yves Saint-Laurent brooch, you need to add a bevel along all the edges… and all the triangles are going to come in your way. Seriously! Very seriously!
If it were my blend file, I’d go back to the original vector import. I’d convert the curve to 3D to keep only the outlines and to work from there. Once converted into meshes and extruded, the Solidify modifier can make nice quads all around everything. Inside, outside, where you need it. You join everything and you fill the holes with [ALT F] (Beauty Fill which makes plenty of ugly triangles) or the Grid Fill. Here the triangles won’t be a problem as long as you have all these nice quads along the edges. Finally, you’ll be able to apply a bevel to make everything smoother.
Lot of work but the beauty has a price.