How do I open a Certificate Trust List file in ProDesktop?

I downloaded a file off of thingiverse.com, a 3d modeling file. The file type is Certificate Trust List. When I try to open the file through ProDesktop, it says that the file is not a Prodesktop file. My teacher wants the file to be in ProDesktop and wants it to be .stl file. I tried opening it in AutoDesk Inventor and it work but then I tried to export it as a .stl for my teacher, a message popped up saying that the model was invalid. I then tried to open it in Sketchup but it said that it wasn't a sketchup file.
Please help, any info helps.
The link is http://www.thingiverse.com/thing:2052282/#files

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I use Pro desktop all the time and it will not open an STL file. It will export as STL though., Try Mesh lab it is free, and will let you open and export STL files.

petercd4 months ago

It is an stl file as rickharris pointed out, you need to change the microsoft default "open with" properties for that file as the default is an incorrect crypto shell association.

Lazyox (author)  petercd4 months ago

So I'll change that to the program I'm using?

petercd Lazyox4 months ago

I dont know which version you're using, but the free version 8 that was available for download doesnt support stl files, neither import nor export.

You might have to use sketchup to open the stl and then save as an iges or other prodesktop compatible format.

petercd Lazyox4 months ago

Yes, but if you don't have access rights cos school computer, it might not allow you to make changes.

Then you'll need to open it from whatever program you're using.

rickharris4 months ago

OK I Down loaded the two files below the image no problems - see picture - They appear to me to be STL files but I don't have anything to open them.

Check your date time on your computer if it is wrong it can throw a cert error.

Lazyox (author)  rickharris4 months ago
Thanks for the reply.
I can open them find at home using 3D builder and it's shown as a .stl file. but when I'm using the school computers it shows it as a certificate trust list file. I can't print it at home as I don't own a 3D printer. I don't know if I can change the date and time on a school computer either, as the IT technicians prevent us from changing anything.
rickharris Lazyox4 months ago

check the time date and ask for it to be put right.