I have an Ender 3 Pro with a 4.2.2 board, which I was getting conflicting reports as to what drivers were on that board and how much of a possible improvement the 4.2.7 board would be. A 4.2.7 has been sitting in the drawer beside me for months waiting for me to find the time and energy to deal with the mess left on the original board from whoever got their hands on a snot-gun during factory assembly... As 'mildly annoying' as the Ender 3 Pro was to put together, I honestly would have prefered having to sort those wires out myself than deal with trying to unplug these leads.
Was half tempted to take wire cutters to things and just make a new wiring harness, but I've gotten most of it out this morning thanks to this tread's timely reminder just prior to a meeting. Only ripped three pin headers off the old board... Might see if I can't get the new board in and running this evening, but I regret that I forget to take a sound recording of the old levels to use as a baseline. It wasn't 'loud', it was just annoying.
My cabinet plans for this was as much storage based as sound control based, and the plan was to allow for isolating the controller board/power supply in a volume that's separate from the print volume, and I can then vent both through sound baffles as needed.
As for cutting steel accurately, you can do some decent work with decent aviation snips on mid to soft temper sheet, and final clean up with a file. I find the trick is to not 'cut all the way' when squeezing the shears. If you use the very tip of the blades you'll leave a crease, but if you stop short of having the tip come together you can maintain a smoother cut. Harder/springier steel is a tad more prone to binding. But if you can find a local shop who can cut the blanks for you, and you're willing to buy a bunch at once, then the price shouldn't be too terrible if you're happy to do final finishing yourself.