Looking for advice on printing a tricky part

[JoeJ]

Your picture isn't showing up. Better yet, please post your factory file since that's more useful than a screenshot

[NoahHornberger]

The stl looks like a non-solid surface. What you need to do is open the file in a mesh editing program and select the border edge (the perimeter) and extrude this down to make some thickness. Then fill in the bottom of that surface with a new super-many-sided polygon. This will make a shape that is flat on bottom and has thickness upwards in the shape of your landmass. In maya this is just a few simple steps. I could take a stab at fixing the file for you if you want.

[DarrenG]

If you could have a bash that would be much appreciated. I've taken a look in Meshmixer but haven't a clue what I need to do! This print is a favour for someone so any help in resolving the issue would be appreciated.