double box it. Secure the model inside one box, either with foam or I just use florist foam, cut, hot glued into the box, the plane is then sandwhich on the top with more foam. The idea is to elevate the model so its not touching the box at all. Support on the main wing roots and fuselage. Now seal that box and put into another bigger box with peanuts. Shipped a 1/48 b-57 from NY to Washington State, no breakage of anytype.