Ok, so I am trying to create some simple x shaped ribs for a wing I'm designing. When I use the rib tool, It will only rib out half of my wing from a sketch I made. If I try and rib the other half from the same sketch It gives me a rebuild error and says that It would result in a zero thickness geometry. Is there another tool I should be using? I tried constructing the ribs separately also but I couldn't get them to join to the wing shell correctly and cut off he excess to make them form fitting.
Are you sure you're extruding the ribs in the correct direction?
It would be helpful to see your sketch. I'm thinking you probably don't have the ribs bounded properly. This means the rib sketches need to be on a plane on or below every object it comes in contact with when the "thin features" are extruded "up to next". Zero thickness is a result of trying to merge two bodies with an edge to edge or corner to corner geometric condition. You may have this result on one side but not the other so it might be helpful to mirror your part if it's symmetrical.
Devin's right. Check your edges and vertices. If all looks good and it's still not working, an alternative is to construct a plane (parallel to a face/parting line for instance), sketch your rib and extrude to a face, drafting if necessary.
OK never mind I got it guys. I just used extrude and made it bidirectional and up to body