Here is another update. I have started making the hidey houses and fixing up some of the details.
@piggsters, that radiator is nearly never turned on, I am heat sensitive. what my pigs get here it will never be turned on. That gap in the top corner is not actually a gap, it isn't visible in the picture but it is sealed up with a small bit of 10mm weld mesh wire. Originally it was chicken wire but I have changed it out because of advice I got here.
@jinxie, I have already gone through a pack of zip ties making this, I am getting two more this evening to finish it off. Funny you should mention sign material, earlier on in the summer I got a huge 10' by 5' piece of corriboard (also called corex and coroplast on this site, but I have always called it corriboard) for free from a local grocery shop. I had intended using it for chicken coops but it isn't really strong enough for use outside so. I am using some of it on my cage. If you look at the first picture the base it lined with a piece (not quite to the corners though). The whole thing is lined with a shower curtain, including 7" of the sides. The loft is very easy to remove for cleaning so I should be fine for that. I am making their hidey houses as big as I can.
The first thing I have changed is their hay rack, I have re-used the wire rack on the original one but made the box from corriboard. I have made a litter tray type thing for infront of the hay rack that also protects the ground from the water bottles and the food will also go in there. I am not sure what bedding will go in there,some pine shavings (kiln dried, dust extracted) or newspaper probably or maybe even back to nature paper bedding.
I have to date made three hidey houses, a hammock and a tunnel.
One corner unit type one made from tree branches and cotton cloth for the roof. The second is made out of a plastic basket that you can get in €2 shops and lined with a polyester scarf on the sides. If you can see in the pictures, the entrance is covered with little pieces of fleece that are hanging down, are these a good idea? The last is made out of little black ikea basket type things that are made of thin corriboard and lined with a material.
I made the hammock myself and I will probably make another one some that they can be changed out when one gets dirty. I really like the tunnel I made and I could make a tutorial if anyone wants one. I made it out of corriboard that I cut down the middle and made into a tube. I then made a liner to go around it and inside it. The great thing about it is that whet it is flattened it pops right back up.
For all the hidey houses I have made liter tray type liners from either corriboard or cardboard wrapped in shower curtain. These can be removed everyday, emptied, wiped down and put back in.
I am waiting on some fleece blankets I ordered online to make a third floor liner and to cut up for little blankets for inside the hidey houses.
I would also like to add that other than the fleece I am waiting on and the cable ties I have bought nothing specifically for use on the cage. Almost everything was gotten for free or repurposed from around outer house.