The LACK is made of very slippery material so it is very important to rough up the surface before you glue. Rough up all 4 sides of the middle part, and one side of the other 4 parts. Then put on the glue (strong stuff!) according to the instructions on the bottle. Keep one centimeter free on the top of the middle part. The sideparts are glues 1 centimeter lower then the top of the middle part!