Mock ring pop candy with a secret compartment to hold a real ring! This design is inspired by this and this design, I created this thing to hold the engagement ring when I proposed to my girlfriend (now fiance!).
The top screws onto the bottom. It is slightly bigger than the actual candy, but uses the same base: with the candy eaten and plastic stem clipped off near-flush, you can glue the fake gem to the base. It can probably be scaled back down slightly depending on the ring size.
Printed this slower than most items (40/20mm/s) and slowed the bridge speed down to 10mm/s to get away from needing supports on the middle nub on the bottom of the gem base. To my complete surprise, printed successfully on the first try, including working threads.
Used generic Super Glue to secure the base of the gem to the base from the actual candy. The base has a nub that sticks up ~0.5 in to hold the candy--I just used my normal pair of snips to trim it close to flush of the top of the ring base.