I'm getting ready to make a heavy dragon cake. I've never used a masonite board before, and was wondering if I could cover it with fondant. My plan is to make a cobble stone imprint.

yes! go for it!!

Thanks! Should I use gum clue, buttercream or piping gel to attach it? I've seen the boards, but have never paid attention to the surface.

i would use water--gum glue yes, piping gel yes buttercream no

and of course be right ready to cobblestone it before it sets up

and then in a perfect world you'd wanna let it set up before you put the cake & stuff on it so you don't mar the surface--let it get a little crusty

you also might want to cover the edge with a ribbon at some point so you don't see the brown board--just attach it with glue, piping gel

Perfect! I plan on making the board two days in advance. This cake will be my first Icing Smiles Cake:-) Thanks for your help!