Solidify Modifier won´t create a solid surface I´m quite new to Blender and wanted to try out 3D printing. 
Now I´ve already created a form and wanted to add wall thickness. I have already diagnosed it with Netfabb and apart from the fact that it´s not closed it is alright. 
My problem now is that I have applied the "Solidify" modifier and it only adds a an unpleasant rim instead of giving it a water tight surface. What am I doing wrong?
Uncheck the "Only Rim" checkbox in the Solidify modifier settings and you will get the expected result.