There is a trick to doing complicated projects. They can stretch out for months,
so it's worth it to be prepared.

The easiest way to do something complicated is to do something simple and build
off of it. For example, when making a saw, start by making a rectangular knife,
then put teeth on it. Even if you only do half the job, you'll still have a nice
knife. In other words, if you have a finished product every step of the way,
it's much easier to stay motivated.

Keep something as simple as possible. Thinking is hard work, but you only have
to do it once. If you have a complicated process and it turns out well, you'll
have to do it all again when you need another one. If you spend a month cutting
the number of parts in half, you could easily make a hundred if need be.
Maintaining things also gets easier because there are less things to break.

Keep a todo list. Being organized makes things easier. For example, when
ordering parts from china, if you have a list of things that you have and have
not bought, there is never a situation where you forgot one part, so you have
to wait twice as long for all your parts to arrive.

Be your own customer. If you know what you want in a product, you know what
other people might want in a product already. You also will care more about how
nice things are, not how much effort they took. It's easy to get caught up in
the mindset of "One hour of my time is worth a certain amount of money," but
it's the usefullness or enjoyment of your product that is worth something, not
the time it took to develop it. You will know when it is ok to cut corners.