4/22 Update: New files uploaded to match more specific bearings. The "Spacerail Replacement Steel Balls Spacewarp Space Rail" available on amazon (https://www.amazon.com/dp/B006PPI71S?ref=yo_pop_ma_swf) will fit the new files perfectly. Message me if you have any questions.
4/16/18 Update: Files have been edited to fit better together and more accurately fit the hole layout on the top sheet metal.
I wanted a filament feeder to sit on top of the delta, but all the ones I found online had significant friction and when i printed one, it seized and caused a failed print. I saw others had the idea of doing marble bearings and followed that model to design a spool mount that should be very very low friction.
I designed this using onshape, and it can be found at the link below.
For assembly, print the side piece twice, you can use M3 screws or just use the same ones that attached the handle and screw them back into the handle from the other side. Then snap in the bottom section to the sides, fill with marbles that are ~15.5 mm diameter (or if you want to try printing marbles for the job, I've included a file).
It is worth noting the biggest inspiration for my design was a user in the facebook group who posted his top mounted spool holder, but that gave me trouble. I do not want to post names here, but thank you.
Don't need supports much, you can probably get away without them on everything except the top section. I would recommend printing the top section upside down so the marble rounded section is smooth for low friction. I always print raft when I have a large section of supports touching the build plate.