When I interviewed Eric Johnson in his Austin-based studio a few years ago, I was struck by something that at the time seemed rather mundane. With his guitar in hand, Eric talked and played, demonstrating some of his approaches to soloing. But as brilliant as that was, what caught my eye was the periodic modifications he made to the his guitar while he played.
You can create your own phase-inverting/polarity-reversing adapter simply by swapping the leads of pins #2 and 3.
A phase switch on an amp or mixer is handy because it can eliminate problems when two signals from the same source arrive together at the summing destination, but at slightly different times, due to a delay in one of the signals.
Packing foam comes in all sizes, and lots of it can be re-used and put to good purpose for padding. If only you weren't looking at a sharp-cornered slab when your instrument and microphone padding needs graceful curves and gentle hollows.
For recording guitarists, one benefit of a head-and-stack configuration over a combo is that you can separate the amplifier from the speaker cabinet and run a long cable between the two. A speaker-level signal can travel a longer distance than can a guitar cable, so in a remote recording situation that requires really loud levels, you’ll sometimes see a head and cab in widely separated places.
If you buy a new instrument of a certain quality, chances are it comes with a case. Usually a good one. It might not be strong enough to endure the gamut of disgruntled baggage handlers at a cash-strapped airline, but you can at least throw it in the trunk of a car or haul it around town without worry of the precious cargo inside getting damaged.