Round off corners of a straight edge prim?

[Rolig Loon 22,411]

You can't do that with standard prims.  All normal prims in SL have sharp edges (well, OK, except for spheres and torii).  If you want smooth edges, you'll need to create sculpties or mesh objects.  For that, you'll need to use a 3D modeling program like Blender.  Unless you are prepared to climb the learning curve to figure out how to do that, the easiest solution might be to shop for packages of prefab sculpty shapes.  Visit someplace like Builder's Brewery in world or look on Marketplace.

[Rolig Loon 22,411]

You can't do that with standard prims.  All normal prims in SL have sharp edges (well, OK, except for spheres and torii).  If you want smooth edges, you'll need to create sculpties or mesh objects.  For that, you'll need to use a 3D modeling program like Blender.  Unless you are prepared to climb the learning curve to figure out how to do that, the easiest solution might be to shop for packages of prefab sculpty shapes.  Visit someplace like Builder's Brewery in world or look on Marketplace.

[Lyra Blackthorne 77]

you could use a texture with the corners made transparent.  The prim would be square but would appear rounded as long as your textures match up right