What's the little potted thing under the Speeduino box?
Yup... Crimped Molex terminations are the way to go. Properly done, they make a stellar connection and with a hand-held crimper you can work almost anywhere.
We didn't have Amazon as a go-to when I was working so we bought the crimpers (both hand held and bench) from Molex for astounding $$$$$$$. The hand-held equivalent of the one you show (very similar to mine) was a shade under $300 bucks! (and how do you spell "Rip-Off?"
Nice progress there, Dan. Your thing of beauty is becoming more beauteous, inside and out.