Why doesn't this model work?

[Bikeracer2020]

Have you sliced it in 'vase' mode. That will literally only make a thin walled vase.

[fozzie52]

Think I worked it out. Seems to be a scaling issue. I made it too big in Onshape so when I scale it down in Cura it scales to only 1 pass-worth of thickness in the walls. Seems a bit rubbish though because now I've made the walls a bit thicker its suddenly jumped to like 20 passes-worth. That "vase" mode you mentioned "spiralize outer contour" makes it so its only doing 1 pass thickness again but that may be something to do with my noob CAD skills as before.