On your butt because most of the questions you have asked have been asked before. Can tell by the questions you've asked you haven't done much if any research of your own. Use the SEARCH function. There are lots of threads about different type of woods and their characteristics, different types of hinges and how each work, ballasting your baits, where to put your line tie, what style of tail, what are the best hooks and paints and clear coats.
Mark has countless hours on this site sharing his knowledge of PVC bait building as well as many others in their area of expertise and all that info is on this site, in these posts. YOU need to do the research to find it. Don't expect someone to hand it to you.
When i decided to make some big slammer style baits, I needed to learn to use a wood lathe. Off to Youtube I went and some 15-20 hours of vids later, I had a good general knowledge of a lathe and how to get what i wanted out of it. Spent a morning working with some 2x2"s from Lowes and I was turning out great bodies before I starting using prime wood.. I also have to say while a lathe is not rocket science, I was very successful right away because of the work I had already put in.
If you were to state, like in your last post, "Hey I'm having trouble getting my baits symmetrical when sanding, what should I try", you showed that your making an effort and myself and others here and on SU will be more likely help you and get you the info you desire .Most of the posts above politely told you to do your own research and try things for yourself.
When your debut post on Swimbait Underground is "Who is the most knowledgeable swimbait builder", and want them to just tell you how to do all the things it's taken them decades to learn(I am not one of them), that offends me and many others on both sites. Do your own research. I have spent hundreds(no joke) of hours on this site searching the forums for info, I suggest you start doing the same.
That is why I've been on your butt