This Lego-compatible planet gear carrier is a companion to my 40-teeth ring gear.It allows for many configurations of epicyclic gearings:
Because of the 3D printing process, holes can be a little bit tight when you receive your print. Corners of the central hole in particular may require to be cleared with a utility knife or a file before an axle can be inserted.
Rounded holes will eventually wear off but you can also help that by rotating an axle in them or using a file.
The 3 cross holes for bearing 16-teeth planet gears are a bit lose. Sandwiching the gears with a secondary planet carrier (that is, the one with a rounded central hole !) might help keeping the axles in place.