How to make 3D parts of a rug?

This artist (https://www.instagram.com/ig.rugs/) makes amazing 3D rugs, and I absolutely love his work! I’m curious about how he achieves the 3D effect. From what I can tell, the base part is loop pile and the 3D parts are cut pile. I always thought that was the key, but when I tried using a high pile cut gun, I found that the yarn doesn't hold its shape while being tufted, probably because the yarn is too long? This is different from using a regular cut gun where the yarn keeps its shape. Can anyone advise on how to achieve this effect?

https://preview.redd.it/odqnijbby1fd1.png?width=680&format=png&auto=webp&s=88be762a90ee8d47204a3c5bbb56af7de400c33c