I marked seams on this mesh. One side looks like this:
From the other side, there is also a seam on the short edge:
No seams on the bottom. I can easily imagine cutting this with a knife and laying it flat was it made of paper, yet blender cannot figure it out. I am getting a message:
Unwrap could not solve any island(s), edge seams may need to be added
I also tried to add seams on all outer edges, again no effect:
So in the end I tried to split the model to have each face separately and guess what? Still the same error.
People were not kidding when they said Blender is impossible to use for new users.
So what is missing? And does this really have to be done manually when I just want to map a seamless texture?
The model in open scad looks like this:
// width and depth of the transformer base (it's a square)
baseSize = 10;
// height of the transformer base
baseHeight = 2;
cube([baseSize, baseSize, baseHeight]);
And here's a ASCI STL "render" of the model that can be imported to Blender:
solid STL generated by MeshLab
facet normal -0.000000e+00 0.000000e+00 1.000000e+00
outer loop
vertex 0.000000e+00 1.000000e+01 2.000000e+00
vertex 1.000000e+01 0.000000e+00 2.000000e+00
vertex 1.000000e+01 1.000000e+01 2.000000e+00
endloop
endfacet
facet normal 0.000000e+00 0.000000e+00 1.000000e+00
outer loop
vertex 1.000000e+01 0.000000e+00 2.000000e+00
vertex 0.000000e+00 1.000000e+01 2.000000e+00
vertex 0.000000e+00 0.000000e+00 2.000000e+00
endloop
endfacet
facet normal 0.000000e+00 0.000000e+00 -1.000000e+00
outer loop
vertex 0.000000e+00 0.000000e+00 0.000000e+00
vertex 1.000000e+01 1.000000e+01 0.000000e+00
vertex 1.000000e+01 0.000000e+00 0.000000e+00
endloop
endfacet
facet normal -0.000000e+00 0.000000e+00 -1.000000e+00
outer loop
vertex 1.000000e+01 1.000000e+01 0.000000e+00
vertex 0.000000e+00 0.000000e+00 0.000000e+00
vertex 0.000000e+00 1.000000e+01 0.000000e+00
endloop
endfacet
facet normal 0.000000e+00 -1.000000e+00 0.000000e+00
outer loop
vertex 0.000000e+00 0.000000e+00 0.000000e+00
vertex 1.000000e+01 0.000000e+00 2.000000e+00
vertex 0.000000e+00 0.000000e+00 2.000000e+00
endloop
endfacet
facet normal 0.000000e+00 -1.000000e+00 -0.000000e+00
outer loop
vertex 1.000000e+01 0.000000e+00 2.000000e+00
vertex 0.000000e+00 0.000000e+00 0.000000e+00
vertex 1.000000e+01 0.000000e+00 0.000000e+00
endloop
endfacet
facet normal 1.000000e+00 -0.000000e+00 0.000000e+00
outer loop
vertex 1.000000e+01 0.000000e+00 2.000000e+00
vertex 1.000000e+01 1.000000e+01 0.000000e+00
vertex 1.000000e+01 1.000000e+01 2.000000e+00
endloop
endfacet
facet normal 1.000000e+00 0.000000e+00 0.000000e+00
outer loop
vertex 1.000000e+01 1.000000e+01 0.000000e+00
vertex 1.000000e+01 0.000000e+00 2.000000e+00
vertex 1.000000e+01 0.000000e+00 0.000000e+00
endloop
endfacet
facet normal 0.000000e+00 1.000000e+00 -0.000000e+00
outer loop
vertex 1.000000e+01 1.000000e+01 0.000000e+00
vertex 0.000000e+00 1.000000e+01 2.000000e+00
vertex 1.000000e+01 1.000000e+01 2.000000e+00
endloop
endfacet
facet normal 0.000000e+00 1.000000e+00 0.000000e+00
outer loop
vertex 0.000000e+00 1.000000e+01 2.000000e+00
vertex 1.000000e+01 1.000000e+01 0.000000e+00
vertex 0.000000e+00 1.000000e+01 0.000000e+00
endloop
endfacet
facet normal -1.000000e+00 0.000000e+00 0.000000e+00
outer loop
vertex 0.000000e+00 0.000000e+00 0.000000e+00
vertex 0.000000e+00 1.000000e+01 2.000000e+00
vertex 0.000000e+00 1.000000e+01 0.000000e+00
endloop
endfacet
facet normal -1.000000e+00 -0.000000e+00 0.000000e+00
outer loop
vertex 0.000000e+00 1.000000e+01 2.000000e+00
vertex 0.000000e+00 0.000000e+00 0.000000e+00
vertex 0.000000e+00 0.000000e+00 2.000000e+00
endloop
endfacet
endsolid vcg