well if you are redecorating the room from scratch, a german look would be some exposed barn beams on the walls and ceilings with stucco in between on the walls, maybe some dark wood paneling half way up the walls. Try to get some period photographs, maybe WW2 themed, and put them up in nice frames here and there. glass display cabenets can be nice depending what you have to put in them. Firearms (non-restricted or dewat) can be openly displayed. NR fireamrs will need trigger locks. The little plastic ones that take a 2 pronged key are fairly unobtrusive.