Yes, there ARE many ways to make a nesting box, but you want to focus on making one that will serve many purposes over the next several weeks and beyond to accomodate not only the kittens' needs but also Momma.
I like an extra-large dog crate ... they are relatively inexpensive at the discount stores (I bought mine at Wal-Mart at 3:00 in the morning for $60.00). The benefit of using a crate is that while the kittens are still real young, you can leave the door open for Momma to come and go as she pleases. If Momma is young and/or inexperienced, she may not stay with them as often as she needs to - you can close the door and confine her with them to ensure proper care.
As the kittens grow and mature, you can easily move the crate to a different part of the house, allowing them to begin exploring the sights, sounds and scents of their environment. Once they are moving around on their own (at about 3 weeks), you can open the door to the crate and let them explore more fully, but if you need to confine them for safety reasons, you can do that too.
I love my crate - Lexus (my queen) actually sleeps in it when we don't have babies.