Deka - Guitar???

 From:  FelixPQ (FELIX)
4588.2 In reply to 4588.1 
Hi klickoff,

this one is easy, even I (a real newbie) can answer it. Since you already have the top surface like you want, you just need to extrude it in Z as much as you want. In the attached file, I copied your based surface on the side and extruded it 2 cm.