Turned out well, definitely captures the feel of the classic Portal test chambers. Nice clean and simple textures.

One thing I noticed though is when you disable double sided textures to get an easier look at the inside, the ceiling's normals are facing outwards. So something to keep in mind going forward, if you want to put a ceiling on a room you need to be looking up from below while placing those tiles when it comes to Crocotile 3D. To fix it, you can select all the ceiling tiles in edit mode and right click and go under faces and select reverse face.