Blender isn’t a program well suited to engineering type creation. I’m unfamiliar with Unity, but I suspect the same applies.
For engineering applications, you’d want a CAD type of program. Fusion 360 is one such package, free for hobbyists. Another is OnShape, a web-based program. Both programs work well for highly technical model creation. As is common with popular software, you’ll find numerous tutorials on the YouTube to aid in your learning curve.
