hi. i'm going to show you how to hollow outan stl for 3d printing. this is the blender default interface. we don't need any of it,so select it all and delete it with the x key. then import your stl file that you gotfrom the nih 3d print exchange like this. oh wow! it's really big! zoom out and you'llbe able to see by turning on the metric system using the world context and then pressingthe n key in the 3d view that the default
download stl files for 3d printing, sizes that are imported into blender are inmeters. what we need to do is change that from meters to millimeters. we do that byadjusting the scale of the metric world. and now you can see that my model is in centimetersinstead of meters. this is a more reasonable size for 3d printing.
once the size is set, now i can turn on themodifier, which is the solidify modifier, that will hollow out this solid 3d object.basically, go to the modifier menu, turn it on, and then type in the desired thickness;in this case, one centimeter. if i press the z key in the 3d view, i can see the insidemesh. note that if i edit this mesh, that interior mesh is gone. that's because i haven'tapplied the modifier. once i apply the modifier and edit the mesh using the tab key, i cansee that the interior mesh is indeed there. there's one other thing to worry about, andthat is the normals, or in other words, the directions of the faces on the inside andthe outside. if i turn on the normals and type in a value for the normal length, i cansee through the little blue lines everywhere
that the surface on the outside is pointingoutside and the surface on the inside is pointing inside. if that's the case, then my 3d printis ready to go. so all i have to do now, once i'm satisfiedwith the model, is export it. do that with the file menu: file > export > stl. give ita name and export.
