Flamemaster or PRC...an aviation adhesive that remains pliable for YEARS. Long ago I fixed a surround on an HX2 that was being given way too much power and it lasted for a few years until it was stolen. FAR BETTER THAN ANY SILICONE OR EPOXY! Can be found at aviation or pilot shops near/at airports. Get "B 1/2"...as opposed to B2, B4...this is the tack free time in hours. Not cheap but positively the best. I'm sure a google search for "PRC" will get you there if you want the best. Put it this way...it's used to seal windshields and fuel tanks on 600mph jets!