I've been browsing PVC window molding for trimming the outside of exterior windows in home centers and online. I also have a few books. But I'm not finding information on how the various pieces/profiles of trim go together to make a window casing, and what the whole assembly looks like when you're done. The windows are aluminum and some site-built wood non-opening windows that just need trim around them. I'm looking for something simple. . . . from past experience with this kind of siding I would like to be sure the top edge and bottom sill slope outward and have a drip channel. I'm finding an array of profiles (AZEK Moulding Styles & Sizes - Profiles for AZEK Moulding) and I am thinking I need a "drip cap" at the top (Drip Cap AZM-197 11/16" x 1 5/8" x 16') and a sloped sill at the bottom (http://Sub Sill Nose AZM-6933 1 17/3...x 1 3/8 x 16) with simple 1x verticals at the sides. Will this work or am I misunderstanding how these pieces work together? They both have odd design features (like the extension at the back of the sub sill nose) that don't seem meant to install on a flat surface. The drip cap has that bump at the top, not clear why or how it would integrate into flashing . . . AZEK tells me sorting out all this is part of the fun of molding. I say that's not helpful and they could at least show some standard installation examples.