Hello I am new to this thread so I hope I have done this right.

Basically I want to build a fender mustang style of guitar, I need a lefty guitar and I have wanted to start building guitars since I started playing, i have tools(or my father does) and I would probably buy a right handed guitar used for little money[maybe a used yamaha pacifica(I heard the necks on those are pretty good)] and then use the neck and maybe the pickups and bridge just attached to the body that I would build,
my father says that it would be really hard and that there would be many problems(example if anything is off with the neck attachment the neck could be twisted).
So basically my question is this, how hard would this be to just build a body and bolt on a neck and reattach the pickups and bridge? Has anyone done anything like this?

Anything is appreciated, thanks.
It's not that hard. You WILL need some specialized tooling, though. A set of digital calipers will make your life easier, and will be indispensable in creating an accurate, snug neck pocket. A machined steel straightedge will also help with the center lines you'll need to work off of when laying out your body and the pickup cavities.

You can go crazy buying luthiers tools, and it may not be cost effective if you're only planning to build a single guitar. You'll spend more on tooling than you'd spend just buying a Mustang. Building one usually leads to building another, though, and the right tools will add to that desire. The most valuable tool is patience, especially on your first build. You'll probably ruin at least one body, so plan your attack so that the work requiring the most accuracy is done first. I route pickup cavities and neck pockets before I even cut out the body shape. That way, if I mess something up, I have less time invested in the piece of garbage I've created.

Look on stewmac.com. They have a set of tools for luthiery, and you can look at it and decide which of the tools you think you'd like to have, and/or buy them individually. They also have a lot of tips and tricks that will make your job more fun. It's not as hard as people think it is, and it's really rewarding. Good luck, and keep us posted.
Thanks you so much for the replies, I'm gonna see if I can convince my father to help me build one since I am not the best with using machines.