Help 3D print no walls

Hi I am new to sketchup, I created a model and sent to a 3D printing site. They replied saying the model had no walls? It was not able to print.

Can anyone enlighten me, thank you

Needs more information. Please upload the model (using the seventh icon above the area where you write your post).

If it is bigger than 3MB, please use a file sharing site and provide a link to the file – use 3Dwarehouse, Dropbox, OneDrive, Google Drive or similar.!AhWZEr_Ayb_tnwZx9QmaT9dFEuqN

Try this, otherwise I will be able to upload in an hour

I can confirm that the download works. Just looking at the model.

There are several problems that prevent this model from printing.

1 Most of your faces are reversed.
Select all, then R-click/Reverse Faces. Select one that is the right way out, then R-click on that, and Orient Faces.

2 The model isn’t made into a group or component
Select all, the press keyboard letter g and make it all into one component

3 The model isn’t solid
TIG Solid Inspector2 says there are problems with Surface Borders (the surface isn’t closed) and highlights two areas:

This may have happened when SU tried to create faces that are too small. I can repair the top right one by drawing the missing face on the very small end with the Rectangle tool.

There are also 17 internal face edges, highlighted here in Xray view by Solid Inspector2.

I’m sorry I haven’t time to track down how to fix those.

Here’s a partially fixed model.
motec v7 partially fixed.skp (1.2 MB)

BTW, none of the dimensions seem exact in either mm or inches. Should they be?

Try this one.
motec v7 fullBox.skp (46.9 KB)

Thanks, Box. Looking good.

It still has a very thin bottom and some rather tight points, but it is a full solid.!AhWZEr_Ayb_tnwokcu0WfRp0X26v

Thanks guys, I made changes called v9 now.

That is awesome help.

If I want to make the bottom a little thicker, say to1mm how do I do that now? Will 1mm be thick enough.

Thanks once again:)