Vacuum forming had it's place back in the day when I first started. It was great if you wanted a custom design and then could Frankencase the components into it. Then when CNC came along, that combined with Vacuum forming was an amazing tool and allowed for exterior finish quality that even to this day is hard to beat with 3D printing....but, FDM 3D printing allowed to work from the inside out and though there was a learning curve for the CAD portion that was necessary, the actual "engineering" of a portable was possible. So at the expense of more finishing work, which really you had to do anyway with you were Frankencasing, you could have a fully structured portable casing which was custom to the design you were creating.
Then SLA 3D printing came into the picture, which though extremely expensive and impractical for this hobby on the whole, it brought the precision of using components that were usually ripped from other parts like controllers to be used in the same fashion that FDM was with the casing itself. So now being able to design components with a stock finish quality, specific to the project you're working on has been another huge improvement to case/component design.
Let's not forget too that 3D printing also allows for the more precise use of custom PCBs, another integral part in producing high quality portable systems. And though I haven't tried it yet, but it is on the to-do list in the very near future, SLA provides the ability to print in different materials like rubber, and the next venture is to start making my own rubber contact pads so I won't have to use tact switches anymore to really give the authentic feel of an original controller. TL9000 (rubber tipped) tact switches have been the go-to for years, but even those may soon be replaced due to 3D printing.
Very exciting stuff ahead and it is no doubt way ahead of vacuum forming on nearly every level. I would invest in the future if you're going to get started in this and as
@Gman said, the Prusa i3 MK2 is the best bang for the buck to get started!