I am currently making two interurban car kits and a Sylvan CNR wooden caboose kit. For all 3 of these, I would like to be able to easily remove the floors. What are some of the ways of doing this? I know that typically people use very small screws through the car floor, but are these typically going into pieces of tapped styrene or tapped metal? What size screws would you recommend? How big is the piece of material that is 'screwed into'. All suggestions/advice galdly accepted.