Speaker tape works well. I used the Alder wood base, before gluing it I knocked down the riidges the plate sits on with a router. After finishing I used the self adhesive speaker tape, which the plate sits on. Something like that along with isolating the tube sockets should help. Someone jeweled the plate on one of the Bottlehead kits, I think I saw the pics in the gallery, but I can't remember who or which kit. Looked great though!
Cheers,
Shawn