I've only used the score and snap technique for all my styrene building needs but a current project requires and 4"x4" square hole in a sheet of styrene about 1-2mm thick. The outside border around the "hole" is about 1/2" wide. This ends up piece would get a bit wobbly once getting close to completion making sanding the inside edge tough.
I tried building the shape out of strips of styrene but it still not as clean and seamless as I want the part to be.
If it was wood I'd just drill four holes and jigsaw out the middle piece and clean up the edges and corners with a file but I can't helpe but imagine there's a more precise "expert modeler" way to approach this.
What's the best and cleanest way to approach this simple thing?