jw_j,
its not the scale model you need to make the lids...if it were that easy, everyone could do it. besides, the 1/18th scale models will not fit properly onto the micro chassis.
you either need the proper equipment to digitize any scale model and then reduce it to the proper dimensions on the micro chassis and then cnc (need deep pockets to do this..) OR spend the time to study and research learning industrial design, with all the proper tools and sculpting from scratch.
HPIsuperfan,
both desgns are completely different. I have an easier time doing curves, than I do straight cuts (like a cuda). It takes me longer to sciulpt a muscle car as compared to a sleek design like a mcLaren.