Many years ago a magazine, I think it was "International Musician", ran a monthly series on building your own solid-body electric guitar or bass.
Episode one contained background stuff about design and necessary tools and the instruction to pop down to your local timber merchant and get a suitably sized slab of mahogany or alder, a length of mahogany or maple for the neck and a strip of rosewood or ebony for the fingerboard.
Then put them all somewhere warm and dry and leave them alone to season. For at least ten years...