Yeah, you can add platforms quite easily all you need are some legs to hold it up like this
i dont think it would be a good idea to add tubes as you might split the top plastic bit but if you did it in the bottom... mm i dont know, its possible but i wouldnt tbh.
i have a zoozone 2 for mimi my syrian
that is her current setup ^
and this is pip and pop my robos zoozone 1
i change thiers around quite a lot though ^
i love these cages, especially the zoozone 2. i think its a great size for syrians
new, they are around £50 on ebay. but they come up second hand on ebay frequently so chances are you'll find one for £10-£20
but the lid needs to be meshed, so they dont escape. its not difficult though