Well, first of all, welcome to the forum.:rofl: Most of us on here have been exactly where you are at your age, a burning desire to build a cool car with limited funds and a million questions. Some of us STILL have limited funds.
But let me play wise old Dad for a minute and try to give you another way to go.
Building a car from the ground up is a more difficult task than it appears. On the surface it looks like you build a frame, bolt on some suspension, plop a motor in it, slide on the body, fill the tank and drive off into the sunset. In reality it takes a whole lot more than that, not to mention equipment and money to do it properly. I'm not trying to talk you out of it, just suggesting that for the FIRST build you start with a running or almost running car. Otherwise you will be spending every free moment for the next two or more years (and every cent you have) working on your car.
As an example, when my twin Sons were about 15 we decided we needed to start putting a couple of cars together for them so that when they got their licenses at 16 they would have some cool cars to drive. My Son Don got a '65 Olds convertible, and Dan got a VW bug that we were going to turn into a Cal Look Bug. They were both project cars. Dons got a tripower 455 Olds, and we bought a second car for parts we needed. Dans was built from 8 VW's in total. In the end, neither car was done until they were about 18, and we had to buy them daily drivers in the meantime so that they would have wheels.
The other thing that will get in the way for you will be girls. You will want to start dating as soon as you get your license, and believe me, your car will take a backseat to your dating...........been there, done that.
What will happen is that you will lose interest in the project, and it will end up sitting. (That is why my Son's cars took three years to build........they discovered girls.)
So here is my suggestion. Stay in school, get good grades, and get yourself a car that you can reasonably get on the road in a short period of time. It may not be your ultimate car, but that will come in time. I didn't get the hot rod I really wanted until after my kids were grown and I could afford it. I had a lot of "ok" cars along the way, but it took years to get the one I really lusted after.
I know this advice is not what you want to hear, but I bet you can find some cool car that is almost ready to run and just needs your personal touches to get it going. Take it from someone who has been there many times, slow driving beats fast walking. :rofl:
Don