Well I had done a lot of work on this thickness finding methods and of course there are multiple solutions and algorithms. But the main problem starts in computation time and resources. Imagine if the there are 1000000 Triangles in a geometry so if your logic is checking each triangle with every other triangle. then it will execute like 1000000000000 times which can take up to several minutes or may be hours to compute. So the real solution must have the most optimized algorithm or even to use GPU computation.
this would give you an approximate thickness, actual values can vary a lot and for the purpose of the priniting you cant really rely on this. I would rather shoot a bunch of rays hrough the model in the direction of surface normals, but even that would not really be safe check.
how to find thickness of Cad 3d file ?