I really must be overthinking something about 3d level design... but I really don't understand how people do this in 3d modeling tools. What about texturing? Collision hulls?
@shaderphantom most engines will generate collision hulls automatically from any mesh you hand in. In terms of texturing it's best to do UV mapping in the 3D software and apply textures in-engine
Source 2 Hammer and Trenchbroom have some editing mode where it locks UVs to let materials repeat when manipulating geometry. Is there an analogous option in Blender...?