1) If I extruded a poly and didn’t select crease edges, the edges looked curved on a quick render, rather then
sharp 90 degrees, which I didn’t really understand.
Carrara is a Subdivision modeller,. meaning that you can Add levels of Subdivision “Smoothing” to the model, without increasing the actual Polygon resolution of the object,.
So,. by default,. All edges are smooth,. which is great for creating soft things, and if you want to make Hard edged objects, like metallic shapes, you can select the edges you need to be hard,.. and crease those, while leaving the other edges smoothed.
or you can Crease all the edges,. it depends on that you’re modelling. (see pic ) of two cylinders, extruded, one has “Some” edges creased,. the other has all the edges creased,. and you can see the difference that makes.
2) Why is that Poly darker reversed? I don’t recall doing anything different when creating it.
Is there a way to control that behavior.
Whenever you’re making a single polygon,. the direction which you draw it, (clockwise or anti clockwise) will create a polygon with normals facing out, or in.
The Darker red when you select it, simply indicates that it’s facing away,. and that’s a good indicator that something isn’t right.
I’m glad you’re getting C8,. but I think this specific issue is due to the way you’re modelling it,.,.
Unless I’m making a specific shape, I’ll generally start by dragging out a rectangle, then fill it, and extrude it up,.
From that basic Box,. I can select and extrude polygons, to produce the shape I need. if I want to join parts of the same mesh together, I’d use the Bridge tool.
If I make a model in different sections,. then I want to join those,. i’d either use the bridge or select the connecting edges of the two parts, and Weld them together.
I think the creased edged in your model, are being caused by the way you’ve built the parts, ..then selected them,.. and extruded them.
They’ll all extrude together,. but those parts aren’t connected,. they’re just placed together..
so,. if you model further,. using “Link Polygons” in the extrude tool,. you can sometimes join the tops of objects and leave the bottom edges unconnected,. which will cause issues later.
The edges which Carrara is “Forcing” to be creased , can’t be smoothed, by simply selecting that option,.. It’s forced creased to make it stable geometry,.
So,. you need to get in close to figure out what’s not connected, and delete or weld parts which either don’t need to be there, or should be connected.
Hope it helps 
Click thumbnail to see full-size image
