model not slicing wall fill issues

hi guys
new to the 3d printing scene and I've bought my self a second hand Anycubic mega zero v1 cheap. now the issue I'm having is I've drawn up an enclosure for a PCB, it looks fine but when i try to slice it in Ultimaker Cura its zero material and zero time to build. i drew the item in Sketchup 2016 then exported it to an .stl file didn't work then i tried to import it into fusion 360 to see if it was a fill or a conversion from a mesh to a solid but that didn't work as well. I'm obviously missing a step some where but not sure where
also if anyone has any suggestions on what a good 3d modeling program is let me know, wasn't a fan of the controls in fusion 360 and Sketchup is a bit basic so maybe something between Sketchup and fusion
the files attached are first exports that i did but seems to have an issue with the infills

you model has no thickness.. the walls must be multiples of the nozzle diameter. So if you have a .4mm nozzle the thinnest thing that will print correctly is a single wall that measures .4mm thick.. you would be best off to make your wall thickness at least 2x or more your nozzle diameter. I use onshape.com for my CAD software, it is free but you r models are free for anyone else to use who has an account.. It is similar to Fusion 360 from what I have read.
I will attach a box i made for an electronics project so you can see what I mean.. I printed it with a .75mm nozzle .

thanks mate i set the wall thickness to 0.8 x2 my nozzle and exported it and now its printing finally and had a look at onshape as well don't mind it will probably use it a bit more in the future thanks for the help

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