You need to add a surface that represents the shade cloth. I downloaded your model and set the precision to 0.000000m. I also grouped your geometry and moved it to another layer. Working in x-ray mode, I created a vertical plane down the center of your support:
I intersected this with the rest of the model and got this (hiding your geometry):
Deleting everything except for the top series of segments and then adding an edge to connect the ends and offsetting it in -x to the origin:
I then used the extrude tool to extend it to the other end and deleted the end and bottom surfaces:
:
Your model is too big for me to upload due to the large number of segments you’ve used to create the geometry. If you use fewer edges on the circles and use the soften/smooth function, you’ll find that they will not only look good in SketchUp, but they will render smoothly as well. Making the basic supports into components and copying them will save a lot of size as well.
This thread provides a good discussion on reducing the file size with links to some tutorials as well: Reduce a file in size - #12 by boardumb
[edited] I grouped your vertical posts and arches into a component and made three copies. I grouped the cross struts into a component with five copies. I grouped the base and canvas each as a separate group (no need to make them components since there’s only one of each) and “moved” everything to separate layers for convenience. I then “opened” each group/component and edited the appropriate geometry to clean things up a bit. Prior to saving, I also purged unnecessary items. The result is a much smaller file: cantilever_a.skp (910.9 KB)
BTW, for the record, the size limit is 3,145,728 bytes:
