Something like the bottom part of a rat sputnik, upside down can work as a central hide. Light so doesn't need supporting. Or a carrot cottage - most hamsters like those. But that would need to go in the freezer for a week.
This is the rat sputnik. For the cage floor, the base of it upside down. The rat sized one works better as it's taller.
Rat sputnik
Carrot cottage
You could probably fit both in.
I think what is really missing though is a shelf or platform on the right hand side. The green shelf wasn't much good as it has holes in and takes up a lot of space.
A shelf or platform makes them feel more secure as they can sit under it and it provides overhead cover, plus it's also somewhere else to go and they like running up to it.
I find the easiest solution for that is one of these platforms - you can choose the length of legs you want for it so it sits just above the substrate. So maybe 20cm legs. You can get 15cm or 20cm (from the drop down menu). And use a bendy stick bridge as a ramp up to it. I like these because they work well with barred cages that have a sloping base because the platforms aren't square so they fit almost right up to the edges.
If you have the base full of substrate, that will be about 15cm deep so that's why I was thinking of the 20cm legs. But - the cage isn't that tall and I think you'd be ok with the 15cm legs as you don't have the base completely full of substrate. So you could have the substrate deeper at the other end. You don't want the platform too high above the substrate.
Hamster Cloud Platform with Solid Birch Legs Description:Hamster Platform with 4 supporting legs. Legs come complete with brass threaded inserts for stainless steel screw fixings to fix the platform and legs to one another.
www.happyhenryshomes.co.uk
I'll suggest more when I hear about his clean outs/hoard etc
