Teshe

Dalton aquatic soil and cap it with something.. I have heard of people using other soils but as mentioned above it cannot have any fertilizer and it will create higher nitrates so you will need to take that into account

What you are proposing will definitely work, they are the best escape artists and finding their way into filters off limit areas etc.
Having access to 3D printer will help with tight fits on structure and support ledges on the walls to avoid collapses.
Can probably get away without heating and minnows make good tank mates
Search in the reptile/amphibian forum for some previous builds

Livingart, do you mean they can probably get away without heating?
Well done for doing the research first, long before adding any inhabitants. I look forward to seeing progress and the final result. If the weight on the shelf isn't a lot, and the shelf is rather shallow, you shouldn't need support struts but that is personal opinion and not based on any experience with this sort of build at all.

Hey guys, I am starting work on a new paludarium for some Japanese fire-bellies and I wanted some opinions/advice. I am working on an ambitious plan for it.
To start, I have this 70L tank, it has a hood with build in slots for the UV lights, and should make escape proofing the tank both easier and hidden.
So now for the complex part. The rough requirements for the newts as I understand them are 30% land, 60% water. So my plan is to make an interior enclosure or reservoir using glass walls and silicone. Inside this I plan to house the water filter, heater (If I need one, I am south Auckland so I am not entirely sure it is necessary), and a water pump that will feed into a small trickle over some rocks from their little island. Here is a mock-up, the interior dimensions are wrong but bear with me!
The complex part is I want to create a planter that slots over this, that will house some small plants, mosses, and a hardy little bonsai. The bonsai will shade the water with its branches and provide both lit and shaded areas for the newts on land. I can 3D print the pot/lid for it, but I am wondering if I will need to add more supports along the two tank wall sides. I was thinking I could add a horizontal shelf along the back that will hold the pump outlet, and can be dressed with some rocks to hide it. Will this be likely to be strong enough if it is just silicone holding on to the sides? Or will I be better off adding in some glass struts in the reservoir? Also, if I add struts, would I be better off having them along the edge to give the most open area in the filter box, or will that affect flow, and the better option be to put a couple of supports central to the tank to hold the lid up?
The end goal is to have a stepped staircase of stones leading to a deeper pond along the front of the tank. I am also hoping this will promote a lazy circulation, as I know the newts do not like a strong current. I am also planning to plant the bottom of the aquatic areas to increase the water cleanliness, as ideally I want to work towards a low maintenance setup once it is established. Who knows, if it works might even be able to get a couple minnows (Done some research and found some that are rumoured to be good tank mates) but that is more a stretch goal and not part of the current planning.
 
I want to clarify I do not currently have any animals waiting to move in so I can really take my time and getting this build right, so any advice or ideas towards my goal would be awesome. Thank you!