I can cut header connecting cables :o and solder them instead of headers, but it does not feel like the best option... What cable would be best to leave a gadget ready to use? What AWG?
Sorry. Your questions make no sense. Cannot read your mind.
Have you tried Arduino boards without pins?
Please describe what you're trying to do in a little more detail.
What kind of arduino board (with or without pins, male or female pins)?
What kind of cable?
If we're talking 0.1" header and dupont line, use arduino with male pin header, female dupont jumpers; you can buy connector housings and pre-pinned wire (rainbow colored cable is dirt cheap on ebay, single strands of specific colors can be had from pololu at an eye watering price). The male dupont connectors that go on the cable are much worse than the female ones. Crimping the pins onto wire is excruciatingly difficult IMO (I spent close to $200 on pre-pinned wire for a lighting project, about as much as every other component, and the custom PCBs, combined, and am glad I did that instead of crimping myself). I would rather solder a LQFP64 package by hand (well, a hand holding a soldering iron, obv) than crimp two dupont pins onto a wire using the correct crimp tool - both in terms of tedium and time.
IMO, if you are going to make up .1” cabling for headers on a regular basis, learn to crimp.
It’s easily mastered and makes excellent connections.
Small diameter wire like 26/24 AWG wires can be doubled up in a Dupont crimp.
Soldering works but any flexing can result in wire breakage.
Crimping Dupont crimps: