While I definitely agree that it is not an easy task, I think these two statements are somewhat at odds with one another. They're both correct, I think, but the second should temper the first just a bit. If a person with sufficient patience, access to the right tools and basic mechanical skills follows the instructions in one of the books written on the topic (or even one of the web pages providing instructions), it can be done.

Yes, what the OP is asking about does amount to building a new wheel. And, no, this is not an entry-level skill. However, it's not so high and lofty that an average person can't learn to do it. Not knowing anything about the OP's mechanical abilities, I do think it's prudent to provide warning that this is not likely to be in any way easy. However, I wouldn't want to discourage anyone with the time and interest from pursuing it as long as they understand the scope of the project.