I always just glue 2 BBQ skewers butted up against the fire wall running along the bottom on the inside of the power pod. Use Bixler's method of wrapping it in some packing tape, and it'll be plenty sturdy.
The problem with wooden power pods is weight. Using light balsa wouldn't be any stronger than the Bixler method with some BBQ skewers. And the issue with 3d printing would be weight as well. Depending on the plastic you chose to print it with it could be brittle as well.
Anyway, there are things that you can do to the original power pod that will greatly increase strength without sacrificing too much weight.
You could do it like that one guy who made the 3d printed arrow pod (forgot who it was sorry) where you just print a lattice and then maybe add a support beam in the back to form a really solid box. If it worked for the arrow on the entire pod, I'm sure it will work for the swappable pod.