Dacron line in 20- to 50-pound strength is suitable for all the Skewer Series kites.
At this point, you've pretty much finished making the MBK 1-Skewer Box kite!
As mentioned earlier, there's more kite making on this site than you can poke a stick at. :-)
Want to know the most convenient way of using it all?
The Big MBK E-book Bundle is a collection of downloads—printable PDF files which provide step-by-step instructions for many kites large and small.
That's every kite in every MBK series.