hi rat....it all depends on the signs them self but 1/2 inch to 1 "....will always work poster can be somewhat larger trial and error works print some see how they look ....good luck....neal
ps....im just finishing up a rod/work shop to display on the bench and under glass models look for it i might post it here also under dioramas only have 1 sign up so far but printed some new 1's today
pss....if u dont want to make ur own u can find sheets of different signs on ebay under models....diorama look for seller scalemodelsby chris or something like that