[mncavylover]

A 2 x 6... Let's see. That would be about:
(2 x 15") x (6 x 15")
=30" x 90"
Then you'd have to add the sides, which are 6" on each side (12" total)
=30+12 x 90+12
=42 x 112, which isn't possible with one sheet. If you still want the 2 x 6, which in this case would be 18.75ish square feet, you'll need two sheets of coroplast.

You can do a 2 x 5, though:
(2 x 15") x (5 x 15")
=30" x 75"
Add the sides:
30+12 x 75+12
=42" x 87"
Which, in this case, is about 15.625 square feet.

Either way, there is plenty of room for up to four, maybe even five, cavies. How many do you have?