I have no idea what is going on with this, no idea what to look up to find answers, so I'm going to ask by myself.
I am relatively new to 3D modelling, and made a mount for a motor using Sketchup. I know, Sketchup isn't great for 3D printing, but it is user friendly and more importantly: free. When I loaded in this small model to print and sliced it, it said it would take 40 minutes, so I previewed it only to realize it has made the model completely solid with infill all the way up to the top. I can't just set infill to 0 for obvious reasons, but, like, why? Is it my fault, Cura's fault, or Sketchup's fault? Posting this to a Sketchup forum too. Running ver. 4.6.0 for Mac.
Attached are images of 1) The model, showing what it's supposed to look like, 2) The infill filling up what's supposed to be hollow and 3) The outer shell
Not pictured is the hole in the bottom, which also is completely ignored.