For this Delta, you need long lengths of 5mm (3/16") wooden dowel. Enough for the 2 leading edge spars of 1.0DL (120cm, 48") and the vertical spar of 0.8DL (96cm, 38 1/2"). Plus the spreader which is less than 0.9DL (108cm, 43"). They are easily cut to the lengths required with a small cheap hack-saw. But don't do any cutting just yet...
TIP: Do your best to ensure the 2 leading edge spars are about the same stiffness. You can weigh them, or just flex them in your hands, to compare.
Now for the spreader, which holds the leading edges apart during flight.
Each leading edge spar will have a shoe-lace tie which attaches it to one end of the spreader.
For the following, you will need to use pieces of electrical insulation tape. Unless otherwise noted, make each one about 4 times longer than it is wide...
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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...
Every kite in every MBK series.