If you want more details, then the construction drawing, layout, etc. If you are self-disciplined, self-study is no problem. There are tutorials online, but I think by going up one flight of stairs may spend more time painting. If you sign up for class, you can learn more pertinently and master skills better; As far as CAD is concerned, the study time of 30-50 days will not be too long. If you master 3d and learn the basics by the way, the cost should be several thousand, and each place is different, so you should choose according to your own situation!