Has anyone here ever had to 3D print a part that holds a PCB, in other words, a PCB enclosure? Is it better to use clips and pegs or screw-holes as PCB supports for such an application?
(let me know if that needs clarification)
I want to say @okyeron might know something about this, although I think he does laser cut not 3D printed. I might also be totally misremembering 
Mostly laser cutting stuff on my projects.
Case/enclosure structure would probably depend on the pcb. Does it already have mounting holes, etc. ?
Then kinda depends on how you want it to look. Too Many choices. 
My default strategy (though there are others) for fastening printed plastics and electronics is just simple nuts and screws/bolts, and to include hexagonal pockets or partial pockets to prevent rotation of the nut.
Gives you the effect of being able to thread your screw into the plastic and put it in with just a single driver. Except you’re not threading into the plastic, you’re threading into the metal behind the plastic.
This also works just as well for fastening halves of a plastic clamshell-style electronics design together, where the enclosure might be totally outside the PCB, and the screws don’t go through the board at all.
You can always use Heat Set Inserts in the 3d printed parts and then screws or what not.
I keep an Adafruit nylon standoff kit on hand:
This lets me attach to metal or 3D printed holes depending upon what I want to do.
Thanks everyone!!