Between 2005 and 2007 I made 25 maps for Halo Custom Edition. I was aged 13-15 when releasing these and learning 3DS Max and the tools to make these levels. I modeled, textured and placed all the objects in the maps as well running radiosity for lighting.
All of these levels are under the suggested cap of 11,000 polygons for Halo: Custom Edition levels, those with slightly more had more intense portaling done to keep optimization while playing the levels.
I made a detailed video going over these maps in 2017: https://www.youtube.com/watch?v=wiS9v4QGAcg
My 25 Halo Maps... 10 Years Later