This might help you cmpolis/convertSTL: A utility for converting STL files between ASCII and binary encoding. (github.com)
I don’t have any, but the one linked by @carolhmj seems nice.
I am sorry (in advance, but not far in advance), but the problem is the stl encoder being used is crap. I imported the file from the original post 584 mb into Blender. Without changing a thing, I export back out as an stl @ 97mb. Looks Identical in sandbox.
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Nice finding there 
That makes more sense to me. I was just following from a distance (didn’t attempt anything, sry) but just couldn’t help wondering what would be included in this file.
this is the link of model you can download
If you open your model in Blender and export as STL, it will be around 96 MB instead of 580 Mb.
No problem to open in Sandbox.
When I saved your 580 Mb as GLB from Blender and then use gltf-transform optimize (Command-line quickstart | glTF Transform) I’ve got the file with the size less than 1 Mb. There are some artefacts, though.
I believe you need to optimize your original file with some DCC tool like Blender before you export it to STL.
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