This was modeled entirely within Blender. As such, there isn't much of a sense of scale to go along with it. Scale it how you like in your slicer. It prints without supports perfectly!

Make sure you print a second, can't watch flank without a working trapwire.

The main STL should work for you but if you want more/less detail I've included the .blend with the subdivision surface modifier not applied. The STL included was exported with 4 levels of subdivision, but if that's too much geometry you can change it. I personally printed it with 5 levels but I don't think it'll make a difference on an FDM printer.