GH - Make Notches at Midpoint of each edge of surface

Hey – very very poor grasshopper skills here. I’m trying to make a template for laser cutting, I have a bunch of shapes and i want to make a .25" notch that is .125" wide at the midpoint of each edge. I have gotten this far but am having trouble getting the notches to be perpendicular to the edges. I also need to turn the linework into a surface and use that to trim the original surfaces, giving me a series notched polygons. Any tips are very appreciated!! Uploading: Screenshot 2024-04-05 092913.png…
Polygon_Notches.gh (13.4 KB)