Back from my holiday and been able to pick up my new Onmi Nest! (Not that I need it yet, the Queen I plan on putting in there doesn't even have workers at the moment).
Decided I was going to experiment and use a field and forest biome kit for the outworld, what do you think?

With the outworld attached directly to the Omni nest, I've pushed a small piece of small tubing through the entrance.

I have also pushed a short piece of small tubing through the entrance hole of the outworld

Using a drinking straw I've cut small pieces to sit over the heads of the screws. This is so I can still gain access to the screws at a later date.

Using about 1/4 of the ground mix of the field and forest biome kit I've carefully added this around the tubing and straws.

Add a little decoration.

This tunnel/tube entrance can be extended with large tubing and attached to other nests/outworlds/test tubes etc.
The ground mix is not dry yet but once I've set I will cut away the excess tubing and straws leaving it flush with the surface. The straws I will block up with cotton and cover over with sand, I'll only need to get at these if I have to dismantle the outworld/nest for some reason.
-Jay