Getting Meshes and Surfaces from Thickened Simple Curves

Hi.

I am trying to get into getting surfaces/meshes from simple curves (to build typography and rings). Unfortunately this is very frustrating, because there is always something that makes things look really bad or is not working at all. The 1st image e.g. is showing meshes that cannot be unioned the way they are. But when the thickness of one of the two is changed, so that they can be unioned, that leads to irregularities that can simply be seen. (And look like I did something wrong or still need to do something much better...)

Also very frustrating is that I don't know exactly which tools/definitions/plug-ins I should have a very close look at. I know there are Cytoskeleton, Exoskeleton, MeshMachine, Cocoon, Laurent Delrieu's thickening definitions. But some threads refer to others. Some definitions seem outdated. Some threads put them all together, but for the (for me) most promising examples there is no definition... Perhaps there are also other tools/definitions/plug-ins...

Has someone perhaps tested all those 'thickening thingies' with simple curves and is able/willed to share a few working of those 'playing around experiments'? Or can someone perhaps show/tell me how to get e.g. for a simple example like the two arcs and the circle shown, one proper, flawless mesh that could be printed in 3D? Or how to get a sea star like mesh from the three intersecting curves? (Things getting thicker closer to the intersection.)