As the thread is quite old and does not have much additions anymore, in honor of my boys moving back into their hutch just yesterday I thought I would share my setup.
It is not the best decorated and definitely not as fancy as some of the hutches on here but it is functional for me and my boys.
My boys (2) live in the bluebell 5ft hutch from pets at home. This hutch has worked well for us but if you are looking for inspiration, this hutch does not hold up well to weather so if your piggies are living fully outside I would probably not recommend this hutch.
Their hutch is in our garage, it used to be only moved in for the winter but due to a new shed it is much easier/accessible for it to be in the garage full time. It has a backdoor which is left open during the summer (aside from overnight), and a smallish window to provide some vitamin D on those colder days when the door stays closed.
Having ventilation is needed for warmer days, and the colder days, so if you are looking to put your pigs in a garage/shed make sure there is a way to create airflow.
There is insolation on the sides, top and back. I am not sure what kind of insulation, but the thick stuff instead of just plain insulation foil.
In the height on winter my boys are sometimes closed up all day, I have a very thick sleeping bag from my Grandmother, and it works great as an insulating cover over the front on those cold days. Snuggle safe heating pads and plenty of hay is your best friend.
As for bedding my boys are on bath mats, I know this is controversial but one of my boys has a small nasal passage, meaning he was constantly having breathing issues with shavings due to irritation. I keep on top of the changing of this, and in winter they get changed every couple of days. If you are thinking of using fleece/bath mats outside please be aware of the risks in doing so.
Some modifications I have made are a ledge of wood along the front to stop the constant falling of wood shavings (when I used them), a wooden "banister" along the large gap for the stairway and some carpet on the ramp.
Generally speaking you want to attach it with something removable to be able to wash it but I did not think of this when putting it on so mine is not removable but I would recommend it. The ramp is very steep so you can either put something on it to make it easier to grip or place a stable hide or something underneath to alleviate the steepness.
My boys have a homemade run attached during the day, made by my Grandad. The boys have two runs, one for inside and one for outside.
This one is roughly 2x5 in C&C sizing, and gives them more space to run and play during the day. It has a covered area and a lid with a hinge for easy cleaning/removal of pigs.
It was originally meant to be for outside which is why the attachment to the cage is DIY, so doesn't look the best but we took steps to make sure everything was/is safe for the boys to be out and around in.
As you can see there is a gap between the run and the hutch, so for an extra level of protection there is a homemade door covering with green plastic garden mesh, as the back door is left open all day.
My boys love their hutch, it was baby Reggie's first day in it yesterday and was very nervous but he is settling in much better today.