I used 3M's super strength double sided tape. 3M's other reck was a VHB but I would have had to buy a case 12 rolls at about 400 bucks.
I paid $287.00 for the ten letters. I'm hoping that I never lose one but 28.70 is cheaper than the lot if I were to have to replace one or two.
If your interested just call Erik at Serria Hobbies and he will take very good care of you.
FYI he is the the guy that made those custom panels on the SAN that had the clarion remote in it.