I decided to make a baritone ukulele for myself a few years ago, because i thought it'd be a great challenge and i couldn't find one in South Africa.
I read a few book on how to make guitars and read some posts on the internet of how to bend the sides. I needed a bending iron, but didn't want to buy one so i welded one at my fathers factory - it worked luckily.
These are a few pictures of the process, and fruits of my labour. It took in total about two months working on it daily for a few hours a day and it turned out to my liking. The sound is quite good, maybe its just sweeter to my own ears.The wood i used was spruce for the soundboard, African Mahogany for the back, sides and neck and the inlays were copper, ebony, and maple.
Trial and error.
Better than sex, almost.