There are a few ways to do this in onshape, including defining the layers of
wood and then having your model cut out of the stack, but also including the
laser cutter mode of kiri:moto (although it will require some tweaking as it’s
designed for laser widths, not bit widths)
Fusion 360 has Slicer which is a clone of their 123DMake software. It very easily does exactly what you are talking about. You can add dowel pins for alignment and you can change material thickness and size etc. Simply output your vector files and cut away!
In fact, I’m 97% sure that torso model is a sample that comes with 123DMake.
(EDIT: I just checked and I was wrong, it’s not part of the 123DMake samples. But I did remember where I’ve seen it. It’s a free download on Thingiverse (and probably other places))