This is the template I use to cut out my covers. I got this template by tracing one of my purchased covers and modifying it a bit.  You can make a cover to look anyway you like.  Just make sure it will fit over your  diapers.  This pattern measures 21 1/2" long - 9" at center - 12" front wing - 18" back wing.  This cover fits a 30 LB toddler and will fit over any fitted or prefold diaper.  When using a fabric that has a directional print, cut the pattern in half and sew a seam in the crotch so the front and back are right side up.  Don't forget to add about 1/2' for the seam allowance.  The Ultrex doesn't need a seam, don't cut it in half 

For the binding you can use any material that wont wick moisture to the outside.  Please see the Air Flow instructions for information on Nylon  Tricot. Cut out a 1" wide strip  of Ultrex.  You will need about a 2 yard strip to go all the way around the cover. This is how you will bind the two pieces together.   Cut the bias tape before you cut out the cover piece

Cut out one piece of Ultrex and one piece of print.  It's best to lay the material wrong sides together and then cut at the same time.

Next sew your elastic on front, back and both legs. Sew the elastic right on the edge.  I pin the two layers together all the way around to prevent shifting while sewing the elastic.  Make sure you pin on the very edge of the diaper. The pin holes will be covered with Ultrex bias tape. Don't pin in the center, this will cause little holes that will leak moisture.  The amount of elastic you will need depends on the type of elastic you use.  I prefer soft stretch elastic. 

Sew the bias tape around the diaper, pulling the elastic tight.  I leave the edges of the Ultrex bias tape raw.  There is no need to fold them over or serge them.  Corners are a little tricky at first, but it gets easier with practice.   Since I only purchased 1 yard pieces of Ultrex, my bias tape isn't long enough to go all the way
around.  So I cut two pieces and overlap them. 

Now the cover is almost done!  All you need to do now is add the snaps or Velcro.  I use size 16 snaps, but any size will do. 

You can add the snaps/Velcro on the front as shown here, or you can put the top flaps on the inside and put the snaps on the sides as shown in the next picture.

I only put one set of snaps on.  This  does not allow for any adjustments. If the diaper cover becomes too tight,  I will add snaps to adjust later. 

this is my favorite cover by the way :) I like the side snaps better 

On this cover I put in leg gussets. 

This is roughly what the leg gussets look like. Cut one Ultrex and one print.   Sew the two pieces together on the curve.  Sew a strip of bias tape on the straight part.  This makes a casing for the elastic to fit into. Once you get the desired gather, tack the elastic down on both sides. Sew the gusset onto the cover with Ultrex sides touching. Edge the cover with bias tape. I made two
covers with gussets and found out my little boy doesn't like them.  I think there is just too much bulk for his taste 

Another example of the cute colors and fun prints you can do.  If you sew clothes for your children, make matching covers!