You need to believe in the value of your project in order to have the passion required to finish it. The value can be for yourself, such as learning a new language or design pattern. The idea could be something that provides value for others, such as an open source project or useful tool.
The final 40% of the project is the most critical, and also the hardest to get through. Everything interesting has been completed, and your passion is much reduced.
This is the most critical phase of the entire project. I can’t emphasize this enough. The success or failure of your project lies in this 40%. As a perfectionist, I get sick pleasure from this phase, but it is still difficult to motivate myself.
Any project released publicly, whether for the world at large or internally at your company, will at the bare minimum be used by them, if not analyzed at the source code level. People love to critique, and small issues get blown far out of proportion and threaten your project with failure and possibly humiliation. I feel this is universal to any creative professional or artisan- so much effort and passion can be wasted if there are even small imperfections.
If the tool is to be released publicly, you’ll need to decide how you will release it and market it. This might be purchasing a new domain, or making a github account, etc. You’ll need to write appropriate documentation. Unfortunately, you *really* can’t half-ass this part. If you don’t make a clean website, no one will use it, and then what was the point? Engineers often neglect this stage because it’s not interesting to do.