Well... my mind, while lacking in so many other ways, is extremely analytical. Some say to a fault.

So I typically don't prototype much but I actually did so on the Anti-Cycle device. That one required testing different configurations to get it "right" once the basic principle was determined. Other projects, such as the skimmer and chiller coil housing, I simply measure and work from there based on intuition or experience and what's bouncing around in my mind. In the case of the chiller coil housing, I measured the chiller coil and estimated what was required to build the housing well beyond being near faulty mechanically. (in fact, I did so for the coil of the next model up from what I currently have for room to grow

) That is... overbuilt like I prefer for general peace of mind. The vacuum area I guessed at as I couldn't find much information or any basic formulas in my fairly limited search. In the end, what my instinct told me, fortunately, worked as desired.
I can generally see what I want to build in my mind and figure out which pieces are the best to start with and work from there. There are times when I will jot down measurements to compensate for my lack of memory but the rest is basically from scratch. I hope this doesn't come off sounding arrogant or worse but it's just how I do it and this seems to work pretty well... so far. You have to keep in mind (no pun intended) that I've been a tinkerer and have been enthralled with engineering my whole life, starting with having taken everything apart at a young age. Perhaps not such a virtue back then but it has helped me greatly in present time.

Curiosity of and appreciation for art and creativity have always been strong on my list of interests. I find a certain Zen in there and always have.
The other aspect of all this is being able to look into a piece of work and "reverse engineering" it. It's quite fascinating to "see" where the original designer was coming from and how he or she overcame certain obstacles during the original design. If you know what to look for and have a relatively good understanding of design and engineering, you can literally see the path taken and the abilities of that individual, whether lacking or far surpassing the norm. This can equally be applied to art and music. The "looking into" a song or painting tells a huge story, well beyond the superficial.
Anyway... enough babbling.
Joseph.