>>23442314
Thin (up to 1mm) layers of polystyrene can be made flexible with a heatgun, thinner ones can be flexible right off the bat and as such layered until you reach desired effect. You can also apply and sand two part epoxy (Milliput is cheapest option and can be sanded to glass-like surface with wet sanding) or use it as a filler. Lastly, you can also simply use metal file to carefully remove edges and finish with sandpaper for smooth effect.

To give some example, her shoulder round parts were made out of 1mm bent around "wireframe" out of straight parts. I'm sure you can do better.