Would appreciate some help with making a full blown complex application

I want to make CAD application for the heck of it, and because I find making it a thrilling experience. Now, I don't know much about writing apps, only wrote a bit of html back in school, but I'm sure I will work hard to achieve my goal once I know how to properly get started with the fundamentals of such a mammoth operation (I think it is).

So for basics, I want the app to make a very customized front-end (which I don't know how to make, I've seen tutorials on youtube but its not good enough), and 2. make basic geometry shapes ( fair goal for V1? haha)

I've done some research over the last fortnight, and sadly can't easily find a way to do this. I hope you can picture it in your mind, what I want to build. If you have any questions feel free to ask here or in dms.

Thanking You