The Radon transform was the first thing that came to my mind, too[0].

It does the same thing, but more rigorously and flexibly. Imagine instead of just looking at the shadows (which are essentially a binary 'this is part of the object/this is not') and reconstructing the surface ad hoc like OP did[1], you could also apply it to a translucent object and reconstruct its interior as well.

[0] https://en.wikipedia.org/wiki/Radon_transform

[1] Not to criticize OP here. It's cool to solve problems from scratch as practice and I don't think the Radon transform is common knowledge.

Hough