Nobody is judging your innate ability to do something. What we are worried about is that A. you have no real experience doing this B. you don't have the neccesary equipment and less than ideal space to do the work, and C. the complexity of the multi color paint. Factor all this together and it stacks the odds against you. There is a real learning curve to doing this successfully and that is why we are worried for you. Crash did not say what he said as a put down. I didn't say what I said earlier as one either. Sometimes even though we want to do something doesn't mean it's always possible. That being said you sound determined and sooner or later you will have success but darn if the odds aren't stacked against you.
If someone had said to me at 18, this is your first job, do it reasonably well, and the conditions were like yours, I would have failed miserably.