Replacement guitar case handle

(Neither this design nor this description were influenced by AI; all original work!)

After many years of faithful service, the plastic injection-molded handle of my acoustic guitar case became brittle and broke apart while I was traveling out of town. Since the metal brackets to which the handle was attached were still solid and functional, I found a length of rope and crudely fashioned an odd/ugly (but functional) replacement for immediate utility; a blatantly pragmatic implementation that was at the opposite end of the design spectrum from the OG skeuomorphic molded plastic handle.

While the rope sufficed (and emanated a bit of a "rock and roll roadie" vibe), I began considering whether I might design and print a more refined replacement. It would need to be very strong since it is a relatively small/thin piece of material that must support the movement of a rather significant mass... my guitar and its pajamas.

After a bit of background contemplation, followed by a couple of prototype iterations in Fusion360, I ended up with what promises to be a very admirable encore the the original. In fact, this design may even outperform the original. Granted, I may have "over-engineered" it a little, but the incremental cost in filament, time, and fastener hardware is minuscule compared to the security of my modest 6-stringed campfire cannon.

To ensure strength at the hinge points, and to allow reuse of the original hinge pins (which, at least on my case, cannot be easily removed), I designed the handle in three pieces; one "Grip" and two "Inserts". This way, the majority of the portion surrounding the hinge pins is solid, without a seam that could fail or wear out, resulting in a drop. With this in mind, I also made a point to slice these two "Inserts" in a very deliberate orientation so that the "grain" or layers of the print are "perpendicular" to the hinge pins. (Not sure if I described that clearly. Hopefully it will make sense when you see the screen capture of how I oriented the parts in PrusaSlicer.)

Speaking of slicing, I chose to slice for PETG with a layer height of 0.2 mm, six perimeter layers, and an infill of 70% in a Gyroid pattern. No supports were needed. For me, this yielded a Gcode file that magically transformed ~88g of filament into my replacement handle in just under ten hours on my beloved Prusa MK3S printer. (At a rough conservative estimate of $20 per 1 kg roll of filament, that's only about $1.76 worth of PETG.)

While one M4x16mm cap-head bolt & nut on each side of the handle would likely suffice, I opted for two on each side just for good measure.

Assembly is pretty obvious/intuitive from the pictures. Simply place an Insert over each of the existing hinge pins, slide the Grip into both Inserts, then insert and tighten the nuts and bolts. The two Inserts are identical and symmetrical, so you can opt to orient them with either matching or alternating screw head patterns; either orientation will be structurally identical.

While I've designed and printed many dozens of parts and mechanisms over the past (nearly) ten years for everything from tools to toys, nearly all of my projects have been very bespoke and narrow/specific in purpose. As such, in my opinion, none have been suitable for publishing or sharing on the likes of Printables or other public venues. After installing this new handle on my case, it occurred to me that there may be lots of other similar guitar cases out there in need of this repair. And at well under $5 in parts, this could be a brilliant solution for money-conscious, yet-to-be-discovered musicians as an alternative to the (at least twice as expensive) commercial handles which also involve the replacement of the hinge hardware as well.

I sincerely hope this handle serves you well! Please let me know if you have questions or, even better, if you have suggestions for design improvements.

Rock on!