People who build these things don't need to ask anyone how. They already know through years of experience. They might ask on the appropriate forum how to solve a specific problem just like folks do here regarding electronics. But for the most part they know what they are doing.Like the Mickey Rooney Judy Garland movies. 'Hey kids! Let's put on a show!'.
Anybody want to hear about it?
Key feature is it can be built in different configurations.
From single and twin up to V16 and flat16.
Would probably build in scale first. Like the old railroad invention patent models.
Do you have a love of tiny engines? How many have you torn down and repaired?
If you have no experience then you can forget about your dream unless you are willing to either spend years of working on tiny engines or have a fortune to invest to have someone do it for you.
And they build these tiny engines out of love. Not simply because they just want a tiny engine. If it was just that they would just go and buy one and save a tone of time and money.