Travel Cage?

Do you have any extra grids and a piece of coroplast? You could make a smaller C&C that would easily fit into your car.

Do you need a cage for the place you are visiting, or for transport purposes?

If it's a temporory cage, the best thing is to link grids using cable ties, and use a shower curtain or groundsheet/tarpaulin with newspapers and fleece for bedding.

If it's for the journey, I presume you can't go and buy a cat type box, or other pet carrier. As PM says, you can make a wee carrying cage from spare grids and corroplast, or would a plastic storage box, with grids secured to the top make do? It kind of depends on the length of your journey etc.

A cardboard box, with air holes cut into it will do, if all else fails, but you need to be convinced the pigs cannot escape! Plenty of newspaper and towels/bedding, then tons of hay will 1. stop the cardboard getting soggy with pee. 2. give them something to burrow in, and munching the hay should stop them nibbling on the box.