I've seen 3D engines in Visual Basic. TRUST ME. It's a LOT harder than it looks. Can you effectively do sin, cos and tan calculations? If you don't understand a single aspect of them, then forget about it. 3D programs are no joke.
P. S. You don't need to know DirectX for 3d. As I mentioned, I've seen them done in Visual Basic.
Oh, also, if you are REALLY determined, I'd recommend a different approach: first, get a different 3d engine, see how it works, make some models or something for it, etc etc. Then try to copy it (manually, not with Ctrl+C), whilst attempting to understand each aspect of it, each line of code. Then you might be able to make a good engine.