Creating and Using Custom Mockups for Portfolio

Hi there,

Looking for some good suggestions/advice. I need to create mockups of my online portfolio. The most difficult is several mockups of trifold brochures with CUSTOM dimension sizes (most mockup generators or PS mockups will not customize the size). I also need to mockup other print work of different sizes, presentations, logos, packaging, and websites for both individual pages and case studies for clients. Any ideas would be most appreciated. What is everyone using to create good custom mockups?  Does anyone use Flipbooks? Mockup generators? 3D rendering?  My brochures and other print work are created in Illustrator. Presentations> Keynote. I have Adobe Create Cloud, Envato Elements (premium), and Freepik (premium). Way back in time, I used Boxshot 4 to mock up my custom trifold brochure.  Thank you.