Use Blender to make a flat three-dimensional illustration

After seeing Patswerk's "Red & purple" work, I thought of trying it with 3D software because I was learning Blender! I don't know if the original author used 3D to make it, but I just want to restore it as much as possible! However, there are still two things I can't do: 1. The rough stroke effect, 2. The black shadow

Let it rotate, it's still quite interesting

After one day, I found the areas that I hadn't perfected before!

1. The rough stroke effect are set using Freestyle geometry, and it's best to have enough subdivisions; otherwise, it's difficult to achieve the texture of the author's lines (I didn't do it very well either)

2. The black shadows actually need to be resolved with 'sunlight'! (Area light, point light, and spotlight don't work well.) I was previously lazy and only used the HDR of the world environment to increase brightness. After adjusting it too bright, it naturally became impossible to have deep shadows.

This is a pleasant and interesting exploration of learning.