I think they are too small, but I can't find much specific information on the web.

A couple of options if you want to make your own:
You could scale these plans and make some from wood:
http://plans.rcmodell.hu/ltwt40.jpg

or, I assume there is a source for styrofoam in Egypt, make your own from Foam.
http://www.flyinglindy.homestead.com/skisandfloats.html
This gives you dimensions that will work. If you want to be artistic you can carve the foam to make them more scale-like. Tapered sides, rounded tops, teardropped tails, etc.