I use the same workflow. And the number of things I designed with those two is just insane. When you want something that doesn't exist, it's the best way to go.
And the Ender is quite fun when it comes to customization. I call it the "Honda Civic of 3D printers".
So far, on mine I added: flat bed springs, filament runout sensor, filament guide, a Raspberry Pi running Octoprint, a webcam, an Octoprint shutoff button that sends the signal to the software, glass print bed, LED lighting, wire management, an SD card adapter, screw thread crank knob, vertical screw shims for better alignment, a vertical shaft flex coupling.... I'm probably forgetting something.
So far, I've used Freecad to make a filter holder for my Omega, design a few pinhole cameras, modify existing pinhole cameras by Schlem, adapt weird lenses to Nikon F mount, make lens caps. I even made a LTM adapter that has a rangefinder coupling so I can use point & shoot lenses on my Fed and my Zorki. This one was insanely hard to measure so that it would all work together. But that pinhole camera that takes 35mm is the one that I would say broke my soul as it took 6 months to design, probably 5 or 6 variations including test prints. I spent a whole spool just on the failed prototypes!