3D Print a solid object How can I 3D print a solid object? 

I am trying to create a coin. I have built a model and of course it's just a wire-frame shell. 3D print services tell me that some faces are too thin. I need to fix that and I would prefer to fill it and make a solid. 

Anybody know of a software or process that can convert the file to a solid for printing?
Well, that probably means that you need to make the coin thicker. With the coin selected, tab into edit more. Press A to select all. Then press S to scale them. You might also want to make the coin's features (numbers, etc.) bigger as some fine details cannot be printed depending on the extruder size that company uses. 

This issue is definitely not caused by the object being a hollow shell. As long as the mesh is closed, slicers will recognize it as a solid object. As a 3D printer owner, I can easily verify that.