Hi, I am trying to print two files which make an extractor nozzle and a lamp adapter. File Lampbase C is the plate for attaching to the profile on the Z axis and the ducting to get the air past other gubbins on the machine and Lampbase E is an adapter to fit C to a vacuum cleaner hose.

The drawing was done on Sketchbook, which explains why they are so 'blocky'

The .stl files are here:- https://www.dropbox.com/sh/0xns0z0m9...1r4umA_Aa?dl=0

The problem is that with file E the funnel part gets filled in as a solid and I have tried all the tricks I know, but nothing works. I have tried Makerbot, Cura, Microsoft and Fusion360 to create a printable .x3g file and they all see the .stl as an open funnel, but close it up on the print file.

What have I done wrong ?????