Thank you for all the suggestions!
I reckon I'll get some pine board and make my own shelf/platform...if I'm sticking dowel to the bottom of the house, I could do the same with a shelf (as opposed to fixing to the bars), and will no doubt need to do the same with the wheel which also needs to sit on a base, unless I make a floor level platform to sit the wheel and sand tray on.
The wheel is the Heureka! wheel found here: (
Rodipet Heureka!
I've also got a load of plastic tube tunnels made by Ferplast so can use those to provide access to the shelves instead of ladders.
What do you do about a sand bath in your cages? I've read you should give ones big enough for them to roll in (30cm x 30cm ideally...think I can get in about 30cm x 25cm using a ceramic lasagne tray. Will then have about 70cm x 25cm floor space for other toys/boredom breakers/enrichment type stuff. Hopefully that will all be enough.
What's the best glue to use for the Dowels? Can you use regular PVA wood glue? Do you know if edge laminated pine timberboard is safe?