Basic fish tank pump (about 15 dollars)
Jar with lid, drill two ( or three holes in it depending on which plans you are doing)
At the end of the tube running from the pump into the bottom of the jar attach an air stone that can be purchased at the pet store
Slap the lid on and get the air stone tube closer to the bottom.
Make a small hole in the top on your hide and away from the opening
Put another tube just inside the hide hole that you have made
You can also use a wooden hide as seen here which is why I have 3 holes in my jar lid.
Here is the whole set up.
The objective is to have the pump, press air into the water, and then the air releases into the other tubes with humidity into the hides you hae the tubes runing to. I would also suggest to put silicone over the holes after you have your tubes in place which would max the air flow as well as prevent rust on the jar lid. I have a humidity read out inside one of the hides and there is about a 25 % difference. I have thought about placing plastic over the hide opening where he walks through in strips like in a walk in cooler in a restuarant which may bring the % up higher but chose not to incase he decided to take a bite of it.
I hope this helps
