I measured the tip of the horizontal stabilizer at just a little under 1/2" thick; the root of the horizontal stabilizer (where the stab connects to the fuselage) is about 3/4" thick. I remember that the "ribs" of the stab (and vertical stab as well) were rather tricky to do. They are not tradictional ribs; they are rectangular pieces which are glued into place and then sanded/carved to an airfoil shape - with a taper! A good sanding block is a must, and a razor plane certainly helps. Do not put too strong a side-force or the ribs shatter (I had to re-glue a few of them as I sanded).