It doesn't. I bought it for this project and it wasn't particularly expensive. I am fine to pay some money for it to get it done right and neat though. I also don't have a workshop or any of the tools for diy. Just a patio and the tools to build up the bike.
Do it yourself? Unless the frame has immense sentimental value
You can silver braze the bosses with a MAP torch and crimp with a G clamp or vice