An object consists of a single edge (two vertices). How can it be made visible when rendering? In other words, how can it be "solidified"?
It can be converted into a curve ( Object Mode > AltC > Curve from Mesh ) and then have its bevel and profile modified in various ways
Two different options:
The options in the modifier's panel are the closes to the Bevel modifier. This does the job, but personally I think you have less control over the generated volume.