Hi Groupustule, sorry for the late response.
To make stuff from 3D to 2D we caculate the where the plane and the 3D objects intersect, then draw a new object in 2D based on the intersection points using the GL.Draw and some related GL stuff in Unity
Oh ok. Idk how one would check if the triangles of the mesh of objects intersect with planes (Maybe on collision check distance of each triangle from the plane? Idk). But that simply means I am yet to study and research more into things before I can try my hand at it and comprehend that haha. Thanks a lot. Ill treasure your comment till I learn things and try replicating your method (That is if you dont mind). Sounds interesting btw n love you for sharing the info.