First I would like to say this isn't a full or complete guide on clipping. I am not going to go over use of different types of clipping (such as the invisible tool), or clipping to keep players out of an area. This is just to make playing on your map like playing a surf map, only slightly less so. First I'm going to go over clipping stairs. Clipping stairs is vital. Just look at an official map to know how to do it. There are a few areas that won't be perfect, but they are mostly clipped well. Just really one thing to go over: the bottom step. Clip the bottom step to match the rest of the clipping. Good: Bad: Clipping trim is also important. Two ways of doing it. Either you can just make a slightly further-out wall of pure player clip. If you have all your brushes totally covered this is fine. This can be seen below: Alternatively you can have sloped paths to the brushes. This is a bit more work, and it requires more brushes. I don't really see an advantage in doing this, but go nuts. Doors with trim are the worst culprits of bad clipping. I'll go over how to do it well. Here's a simple door with some trimming. A simple solution is to do something like so. Not my ideal clipping situation, but it works for most people. I prefer to see something like below. I turned the trim into a func_brush and removed collision. I then slanted the edges of the wall itself inside, made them func_brushes and removed their solidity. You will glide through this door. It's great. One final thing to cover is bounding boxes. Please clip things like this. It really just simplifies things. You may also chose to nobuild them depending on some factors. Hopefully you learned something from this. Here (Right click, save as) is a copy of the map I used for the bounding box and door. If you would like me to run through your map and show you any clipping problems just pm me or message me on steam. This tutorial isn't final. I may add to it and/or update it, so feel free to leave input.