A question I get asked every year is what can I use to get better renders from Inventor besides the Inventor Studio as that is a bit cumbersome and not very user friendly.
My answer to that question was to take that your model and import it into Showcase which was still available as a legacy software if you are on subscription as you could still use a few versions back according to the EULA. Unfortunately it has come to a time now that you cannot use 2017 software legally anymore and so we need to look at the stable of software that is currently available from Autodesk.
I only mention Autodesk as I have scoured the globe and unfortunately no one has created an external rendering program that compliments Inventor. One option in Inventor is just to activate the View tab and using some basic lighting reflections and shadows, you can get some pretty good renders if you want.

Inventor is very good at shiny materials but they are all flat. What do you do if you want some imperfections in the material like rust or maybe some very realistic looking bump maps? Inventor can do bump maps (not very well in my opinion) but for rust and being realistic? It can but you will need to manually set it up and it can take some time..

This is where I would suggest going to 3DS Max. Now you might think hang on, isn’t that extremely difficult? Yes and no. For advanced 3DS Max functionality I would definitely say yes , but when you are working with product design and bringing in your model already prepped from Inventor it is a much quicker workflow. Import, modify materials to be accepted by the renderer you use (probably Arnold) and then hit render.
I suggest 3DS Max as it is included with both the Architectural and Manufacturing Collections. So if you are paying for it, why not use it.
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