Summary

OK, this is just my take on the cable management for the E3 V2. My main principle in making things is that it should be as simple as possible to be efficient. Well, maybe this design is not necessarily the simplest, because it involves a lot of rewiring, but I decided to do it this way after reviewing a ton of options out there with different drag chain designs, etc. I had to take the whole casing for the electronics and the power supply apart, drill some holes in the top cover and install some rubber grommets. All cables are original, except the extruder motor cable - I replaced it with a longer one.

I only used ONE drag chain for the Z-axis, putting the X-axis cables through it as well. The cables are not coming from under the printer base (the factory design), but put through the hole drilled in the top cover near the power supply terminals. Then, all the cables going to the extruder (it's a direct drive mod, so no Bowden tube) and the hotend are just fixed to the mounting bracket installed where the original extruder was. The Z-axis drag chain is attached to the same bracket. No need for a drag chain to the extruder/hotend - that cable bundle flexes nicely while being secured at both ends, and doesn't get in the way of anything.

As for the heated bed, you can see on the photos how the cables were rerouted. The end result - the cable bundle inside the original mesh sleeve is neatly out of the way, doesn't catch anything and works pretty much the same way as if a drag chain was installed there. I used a short length of a plastic tube to stiffen the bed end of the cable and prevent it from bending upwards.

I did a quick and dirty Sketchup design for the Z-axis drag chain mounting brackets (source file is included), then drilled the holes in place to secure the cables. The attachment points for the drag chain are designed for the M3 heat-set inserts, and may not fit the chain you have. If you want to print the brackets, be aware that your slicer may complain about geometry errors - just ignore them, it slices and prints OK. Or you can design your own, or pick some from dozens of things already published. This is just to give you an idea of a neat and efficient cable management option.