Why won't this become solid

I’m trying to make a complex shape with a cavity in it. After doing all my geometry constructions, I was able to solid mate 2 solid groups into this shape. When I ran the shape through Solid Inspector2, it shows a couple hundred short edges, and recommends I scale up my model. My model is already in 1000x scale, and nothing changes when I make it even larger (I’ve gone up to x10E6 scale) so I seriously doubt the model scale is whats causing the short edges issue. SolidSolver is no help either, as it tells me I have to remove faces from the model. I have no idea which faces would need to be removed that wouldn’t just cause more problems. Can someone show me how to make this a solid please?

MAKE_A_SOLID.skp (3.0 MB)

you have no material ‘thickness’ in the corners…

then delete any new internal faces…


I scaled your SKP up by a ridiculous factor, then it fixed to a solid using my SolidSolver.
Then scaled it back down to your original dims.
You have an excessively segmented arc forming the ‘ears’.
I suspect tiny edges causing the issue.
A limitation of SketchUp itself - not any particular ‘extension’…
Points closer than 1/1000" are deemed coincident - thus preventing tiny edges getting made and any related faces are also not created !
Unless a ‘container’ only includes faces and edges - and every edge supports exactly two faces - then it is not a “manifold solid”…MAKE_A_SOLID.skp (770.2 KB)