Aluminium extrusion profiles are widely utilised due to their potential to enhance energy efficiency and reduce costs. In this paper, two advanced tool designs for a novel sideways extrusion technique, the Unified design and the Guided design, were proposed. These designs facilitate the production of three-dimensional curved profiles with marked asymmetry and large-scale cross-sections. Numerical simulations of the initial designs revealed considerable variations in bending shapes compared to the target profile. Employing the Taguchi method combined with grey relational analysis, the study identified that the extrudate's bending shape are influenced by the die orifice position and the speed ratio of two rams with different sensitivities. Following this, optimal designs were derived for both design types. For the particular profile in this study, the simulation results showed that the optimal Unified design permitted better welding quality and lower extrusion force. However, the optimal Guided design achieved a bending shape more aligned with the target shape. It can also provide enhanced stability in the extrusion system and higher production yield compared to the optimal Unified design.