I have added an initial design page on the Wiki here: http://www.fsdeveloper.com/wiki/index.php?title=SDSX_Design so far it only contains the document for 3D models (it is the same as I discussed with you Arno, except I moved the LevelOfDetail around so it is simply a conditional display option like everything else). Noticed I have not wasted my life adding methods, fields, etc to the class diagram, and I do not see the need for such detail - it would just duplicate something that can as well be expressed in actual source code. I am aware the information I provide with the class diagram is not enough, but I do not know exactly which parts people would find unclear. So please have a look, and post any questions here - then I'll update the wiki with details as required and we should get the details we need, instead of a 100 page document with trivialities everyone would know anyway. If you have any suggestions to a different (and potentially better) domain model please post it here on the forum.