I just got some Pagoda-2 antennas from Farvew.com and they provide an STL for a protective shell but I was concerned about the disks getting out of alignment, so I whipped up some spacers. The design thickness for the top is 3.65mm and the bottom is 10.45, but on my printer they come out a hair thicker than that so I used a bit of sandpaper and a caliper to get them to exactly the proper thickness.
I was planning to secure them with shrink tubing but the only size I had that fit was quite a bit bigger than necessary, and thus the first time I tried to fully shrink the lower section I melted the spacer a bit. What I ended up doing was using a bit of UV epoxy to seal the edges of the pcb to where it meets the spacers. Glue should also be fine. For EXTRA protection, one could even use this And the outer shell at the same time.
ABS is recommended. I used one perimeter with a 0.5mm nozzle.