Ahh, I see what you mean! At this stage, I only know how to steal the collision off in-game items (so something vaguely eiffel tower-shaped of any size, I'd be able to shrink/grow to the correct size and use that) but not how to create a brand-new custom mesh for collision use. HOWEVER! I did note this video linked in another person's query, and it looks to be doing just that-- the video looks thorough and makes sense, though I've not actually attempted to make a collision mesh using it's instructions just yet-- unfortunately, it does require the use of 3DS Max. I know that the eiffel tower example was just a suggestion, but to continue the use of that particular example-- something I spend a lot of time doing whilst modding, is using the Archive Browser feature of Nifskope and looking at all the random bits and pieces in the vanilla Fallout - Meshes.ba2 file. When I spot something that's vaguely the correct shape for whatever I want to make, that will usually be the one whose collision I steal-- I'll start my custom mesh and add in the stolen collision at the end rather than build it into the collision I'm stealing, because I find it too messy. Well, moriartykain, you've given me the motivation I need to get this tutorial started-- here I thought I'd be procrastinating it forever!