Custom art/Weight mod for Dreamcast Agetec?

Anyone have any tips on how to go about putting custom art on a dreamcast agetec
"green goblin" I see its not practical to put stuff on the metal plate and I have no idea about plexiglass or anything.

Also I see its a bit lighter than alot of the stuff coming out. Any suggestions on stuff to put inside or where to put things to add weight? I remember seeing a mod for a rock band guitar where a guy hot glued a bunch of heavy washers in specific spots to add weight. Anyone else do any weight modding?