if it's just little plastic objects well, that's stuck in the realm of knickknacks / Junk IMO. And I suspect most people will quickly get to that point after the first cheap 3d printer shows up.
It could really revolutionise some things, like home appliances. The little plastic latch on your appliance break? Print out a new one. The plastic flap that keeps your battery in on your digital camera break? Print out a new one. Suddenly a lot of devices might be much more 'repairable' now.
For things like appliances most manufacturers already sell replacement parts for cheaper than you could "print" them yourself, without the problems associated with printing it yourself.
For things like consumer level electronics, the manufacturers could sell replacement parts, but they'd prefer people replace the entire item. If the camera manufacturer won't sell a replacement flap, it's unlikely they'll give out the original CAD files for people to print their own.
It could really revolutionise some things, like home appliances. The little plastic latch on your appliance break? Print out a new one. The plastic flap that keeps your battery in on your digital camera break? Print out a new one. Suddenly a lot of devices might be much more 'repairable' now.