Frustration

My suggestion is to walk away when it gets too frustrating and just take some time out. Go have a beer or something. If you really love the car, you'll come back to it later and things will be easier when you've had a chance to blow off some steam and think about the problem at hand.

If you look at working on the car as your hobby and don't focus so much on the goal of completing the project, then you can have fun with the work, solving problems, researching different ways to approach a task, and figuring out ways to reduce costs.

If that doesn't work, sell off the project and just go buy one ($$$$) from someone who's already done the work.

Someone once said it's about the journey, not the destination. If you love working on your car as much as you'll eventually love driving it, you can't lose.