3D printers 1 Additive manufacturing technology 1 Additives 1 Build direction 1 Build direction assignment 1 Continuous constraints 1 Gradual evolution 1 Optimization algorithms 1 Optimization procedures 1 Self-supporting constraint 1 Self-supporting structures 1 Shape optimization 1 Topology 1 Topology optimisation 1 Topology optimization 1 additive manufacturing 1 build direction assignment 1 gradual evolution 1 self-supporting constraint 1