This is something I made ages ago and have used for a long time. It occured to me just now that it might be useful for other modelers.
It's a set of simple geometry outlines of common TF2 measurements. 64, 128, 256, stuff like that.
Since the grid in various modeling programs can be hard to count off correctly without typing in values, I found this useful to have as unselectable objects in the viewports to ensure I'm snapping to a Hammer-friendly grid.
Each is clearly labeled. Just import them into your modeling program of choice. You might get a warning "scene_material not found" which is perfectly safe to ignore as the material is irrelevant.
There are no usage rights on this. I don't care what you do with these, but I hope modelers find them somewhat useful.
If you don't make models, this will be of limited use to you.