I use the 2" foam I get at hd comes 2ft x 8ft x2''and I use gorrilla glue to put 3 pieces together , depends on your deke thickness . I carve with a hand saw, sure form and rasp file ,tyhen i use acrylpro mastic with burlap ,let dry overnight then another coat light more of a touch up coat to make sure all burllap is covered , let dry for a week as warm and low humidity as pos,thjen i install my keels made of 1' trex deck material, then 2 coats water base valspar ,and then kilz primer ,then finish paints . The batch im working on now is White Wing Scoters and Buffies that I sprayed with rustoleums rubberized black paint a really tough finish . If I can fig out pics here I would do... but typing is a challenge enough . you should check out working decoys .net has a lot of helpfull info and great guys just like duckboats,