if any one is building kite boards i have alot of blind threaded inserts these are the ones you cant screw the bolts right throught the board ( they are for your straps and handle) you can not buy these from any shop or store in w.a i had them made on the east coast and can not use all of them, if you need some just drop me an email there only $2 each
and i have heard of ss tee nuts and have use them in the past they have a problem with bolts going through the board and the cost

they take 6mm , thread depth 9 mm and 12mm long but are set up so you can take off a 1mm if you need too to suit board thickness...