Hi Daniel - look closely at how your surfaces come together - probably the whole thing could be greatly simplified - What did you use to create this?
ShowEdges > Naked edges to see all the nakeds.
@danielbgreenway - here’s a clean version - it looks to me like you did not use OSnapping (Object snaps) to the Ends of previously placed edges, so many of the intersecting edge were quite far out of tolerance - OSnapping will help ensure that you get things more precise - Things do need to be precise in Rhino in order to close your objects and not have bad objects etc. See Help on Precision modeling.
Untitled_Closed.3dm (148.8 KB)