STL File Path Closing Expert

I have a Blender project I exported to stl to send to an acrylic laser cutter, but realized after that I had some open paths. I've attached a picture, there are 4 shapes that are like this, I just need the paths closed, but it's been 15 years since I've worked with 3D modelling software, and would rather have someone with more experience do it.

Please include the word "ceiling fan" with your bid so I know it's not an automated bid and that you can complete it for the amount bid.