This is my first fusion 360 project, it's still work in progress, so keep an eye here for future updates, and for other projects that will come.
You have 2 files, the base and one side, which you can duplicate because it's the same.
I've printed with 0.2mm layer height, 10% infill, 5 top layers (but i see very little gaps, so i'll suggest you to use 6), 3 bottom and 3 perimeters at 100mm/s speed, 60 bed temp and 220 nozzle temp.
Before you put the concrete/plaster in the mold, make sure that you secure the printed parts with some zip ties, clamps or even sticky tape or something. After that you need to oil the inside of the mold for easy release. Then you can put the concrete in the mold, you can vibrate with a rubber mallet or something that vibrates (i know what you thinking :) ...).
I used some fast drying construction plaster so for me 15-20 min. was enough time until I could pull out the planter
NOTE: you can use some force for pulling out the base because it's like vacuum sealed.
Design updates will come soon for some built in clamps for easier securing of parts.
Stay tuned :)