I share my house with two of the two most spoilt guinea pigs in the world...
Their favourite activities include eating and growing, and within weeks they'd outgrown their original run, which according to official how-to-raise-guinea-pig data is the right size for two adults. So, they had a series of cobbled-together extensions and temporary runs, before I put my thinking cap on, gathered hammer and nails, and made their current accomodation.
It's hard to get a decent picture showing how it's put together, so please bear with me.
The room they're in is quite narrow, so I built a 30cm high freestanding mesh wall as long as the room is wide. At the bottom, the mesh is sandwiched between two slim boards which are nailed together, with a much larger board then nailed to the back (the inside-the-cage side) for stability and strength. If I want to make the run smaller or larger, I just move the mesh wall forwards or back.
Inside the run is lined with sturdy, good quality lino, which is cut to come up the walls a few inches as well as cover the floor. The boys are litter-tray trained, but it's better to be sure than have a stained floor!
Here's what it looks like:
Inside, showing the lino coming up the walls:
The lino 'floor' is covered with old towels folded in half, and that covered with a layer of polarfleece. The boys' are toilet trained well enough that the towels are still clean at the end of the week when I change their bedding, so they just need a light wash to freshen them up.
The big green 'piglo' has a litter tray inside it, and there's also one in their 'kitchen' where the veges are. The run's just been cleaned out and new bedding put in before I took these photos, which is why everything's so clean. It doesn't stay that way!
And here's what makes it all worth it: