I can see how what I said made it sound like that was the problem. I actually just did that tutorial, and used it to learn how to make locations. However, maybe I'm being a little too overzealous, and I'm using pieces that don't exactly go come from the same theme set to make something particularly imaginative. Except for this particular junction, I don't have an issue with gaps, as I fortunately did learn how to do snap to grid. Suffice to say, I'm using one of those pipes hallways from the Project Purity quest, and they are leading into an Enclave themed bunker. However, because none of the doorways or anything from the Enclave tileset work with the particular size and shape of the pipe hallways, I was about to give up, but I found a piece of the control room with a perfectly spherical "hole" that I could use to cover up the gaps between the pipe and the walls. However, the hole is actually a black surface (its not intended to be entered), and is even invisible from the inside, which is perfect, as I can have the pipe leading out of the hole, then looking back, it looks like thats where the player came out of. My problem is, the black surface is impermeable, so I had been hoping for a way to make that room piece have no "substance", so it could be there to clean up my mess, but would not interfere with using the pipe hallway. That being said, I'm having heavy duty crashing with the setup I have, and as I'm new to this, I'm not sure if its something I've done. Do any of these things dramatically increase the odds of crashing? A. Having room pieces overlap with other room pieces? B. Changing the scale of room pieces? C. Changing the axis of room pieces (making them upside down, or vertical when they were originally horizontal)? Or do incomplete cells have a high tendency to crash all the time?