Hi hammy2. Great cage for a Russian dwarf by the way.
I use a second hand Gabber Rex (similar shape and size) and although I can`t take a photo of my cage/layout, I can give you some idea of what it`s like inside.
Left hand side: Spare mini Duna plastic shelf slotted between the top & bottom parts of the cage, just as it would be on the mini Duna. It`s not long enough to reach the opposite end, but you can place either a wooden bendy bridge under the loose end, or use a cardboard box/tissue box/small show box under that end to balance it on. I have on top of the shelf a smaller cardboard box with a door in it where Chubs sit in the evenings eating his treats!
I use a wooden bendy bridge to go where the ladder/ramp would normally be or you can use anything you feel is suitable. Duna shelves usually come with a plastic rung ramp, but the bendy logs work well if you don`t have the plastic ramp.
Under the shelf, I have just that. A long tissue box (open end down) so it has no floor. This allows the hamster to dig down into the substrate. Free/cheap, chewable and easily replaced.
Water bottle: Well if you don`t want to use the hole in the ZZ cage, there are two other ways to have your bottle inside the cage. The one I use is this: I use a cut off section of a bottle holder that comes with a Savoc Rody cage. You know the plastic insert that fits inside these tanks and holds a water bottle? I cut that part off using a Stanley knife and slot it into the same central part on my gabber rex and slot a couple of folded pieces of card in to hold it steady. It holds a mouse-sixed Classic water bottle or a hamster sized one. Or you can make a bottle holder like the one I will post an image of from a used plastic water bottle.
Other end of the cage: Silent spinner wheel, another up-turned cardboard box from Cadbury`s mini rolls!
He does love his cardboard boxes! An egg box with holes cut out either end for playing in and chewing.
Chube tube, which he loves. Uses it mostly to hide and pee in!
So just a few pointers for you. Shame I can`t take a photo but hope some of these ideas help. x