I am going to lay a concrete base 5m by 6.2m. At one end build a pair of breeze block Arks, each 2.5m wide and 1.7m deep, each will have light and a heat lamp behind a bar where piglets can lay, and will be high enough to allow easy access for cleaning. I haven't fully yet worked out how to fix a partition to reduce draft across the door but maintain ease of access...
The run will comprise 3 pairs of panels, I.e to form the two sides and a middle divider. These will be Bateman mesh panels or similar and hung so they can be opened out and closed at 90deg, this would enable the pen to be used as two units when the pigs are farrowing but be reduced in size to contain a pig if needed, or allow both pigs to be together in the larger area when they are not farrowing and it is just being used for bad weather reasons.
The remaining end will have two panels. Any of the outer panels could be used for access.
Any better ideas welcome.