3D printing is great, assuming something is made out of one piece. Most things aren't, however, so there would still be a need to assemble a finished item form the various pieces; not to mention the electronics involved. Perhaps if I were to go into business selling mods, one might be in order, however, spending $1000s to save $200, or so for a ProVari doesn't seem wise.
3D Printing has it's place.
We do Injection Molding. To be able to make a Prototype Part in 5 Hours for a 100 Bucks or so is a Huge Time and Money Saver.
A typical Die Set to make the same Part would require 4-6 Weeks and 3 to 4 Thousand in Programming, Material/Cutters, Salary, etc.
And Changes to the Part are Many Times Very Difficult to Achieve.