I have found it, and have finished testing it.
The HPRC 2550w.
The way I understand it, HPRC is an Italian company that is a competitor to Pelican.
I really wanted a hard case for 3 Elektrons that was certified as carry-on luggage. I don’t like taking chances (especially with my gear), and getting a larger Pelican case that may or may not be allowed on a plane was simply not worth it to me. The one flight crew that wouldn’t let me carry on a larger Pelican case with 3 Elektrons would be the one that loses my luggage, and that’s not worth the gamble. Plus, the 1510 only holds two Elektrons comfortably, and you need at least one PL-2 because you have to stack them. You could try to hold 3 Elektrons in the 1510, in the upright fashion, but you lose a 1/4" clearance with the 1510, and with the MD & MnM protruding jacks, you would risk compressing the jacks. Not worth it. That extra 1/4" makes a big difference.
The HPRC 2550w has larger interior dimensions than the Pelican 1510, but is roughly the same size on the outside, meaning you can fit 3 Elektron boxes inside, like this:
internal dimension 510x285x208(mm) - 20.08x11.22x8.19(in)
external dimension 559x350x233(mm) - 22.01x13.78x9.17(in)
It took me a couple hours of picking the foam, and then manually cutting the foam, but I managed to safely squeeze in an Analog Rytm, an Analog Four, a MonoMachine, a JLCooper FaderMaster, and a Mackie Mix5.
Since the interior dimensions are just barely on the edge of allowing the Elektrons to sit in this fashion, the lid does not just fold flat when it is full of gear. Part of this is because there is less room in the middle as some interior space is taken up by the extendable handle. However, even with slightly less room in the middle, that interior measurement in the middle is still larger than the Pelican 1510.
But with a little light compression with one hand, you can latch it shut with the other hand.
I was concerned that there might be too much compression going on, so I took out the foam in the lid, and it closes with one hand just fine. In fact, there’s more than 8mm clearance between the middle Elektron box and the inside of the case lid without foam. Remember that extra 1/4 inch I was talking about? So the foam is just making things that much more snug but not harming anything.