Thanks! I'm really happy. Since they moved in a couple of days ago from their pet shop bought cage I have seen a massive change in their behaviour. They are both more active and popcorning like I have never seen before. Its so nice to see, I could watch them all day! I have spare grids left, because I was originally going to close the whole cage because we have a cat. But she is very nervous and if the pigs come towards her she will run off. She just likes to sit on the bed at a save distance and watch them. The grids are quite high and she is too nervous to jump into something she doesn't know.
Its a piece of square guttering with fine sandpaper on it (attached with double tape) They love the ramps and keep running up and down. I have since made the cage one grid longer aswell so they have got a bit more room.
The gutter works perfect but I have since replaced the sandpaper with carpet. The sandpaper seemed to work fine at first, but I noticed his front nails became quite short and I wasn't sure if it was comfortable for them to run up. So I have put some carpet on instead to prevent them from slipping which works fine!