Pros: this method does work for creating an arch, the tutorial is clear and the writing is simple and to the point. the spiral staircase is informative and useful. the inclusion of the settings is a nice addition to allow easier useage of the tutorial. Cons: i dont think this is the best way to make an arched walkway, there are much simpler ways of doing it that will result in faster compile times as well. Improvements: i think as far as making an arched doorway, you should first create a block shaped brush that is the size you want for the doorway. next make a cylinder brush to use as a guide. place the cylinder brush overlapping in one of the hammer views with the block, and use shift+x to cut the block into the shape of the cylinder. after the block is cut properly delete the guide cylinder and usually you should group or tie the archway to func_detai to useup less resources. Notes: this method you have here works, but for simplicitys sake and not having to using the vertex manipulation tool i think there are better, easier, ways of doing this. if this method works best for you then great use it, but i think its important to include that there are other methods of doing this. btw, my alternative method explanation is pretty bad i know.