I'm looking at creating some semi-realistic symbols for miniatures battlemats, similar to those like "Game Mastery" flip mats and mat cards.

I'm trying to make semi-realistic symbols that match all the classic/basic symbols. (Examples: a rectangle for a door, a "S" in the line of a wall for a secret door, a "U" shape with the inside of the "U" filled in for a fireplace, etc.) But I'd like to double check on what I should do for several of these. What do you think?

Secret Door: not necessary because the battlemat view of the map shouldn't show secret doors
Concealed Door: see above
False Door: not necessary--it should just use a regular door symbol
Locked Door: I have no idea how to show that a door is locked in the battlemat view. The classic symbol I'm using is a door symbol with a large dot in it.
Locked and Bolted Door: see above
Barred door: a door with a metal bar across one side.
Illusionary Wall: it should look just like a regular wall in the battlemat view
Covered Pit: again, it probably shouldn't look like anything different than a normal floor tile or maybe a floor tile with a rug.
Trap door in ceiling/floor: I don't think these are intended to be secret, so I could add some opening mechanism. But how do I show one for the ceiling?
Secret trap door: in this case however it should probably look just like the rest of the floor

If you have ideas of how to illustrate these in that semi-realistic style or samples to point me to or opinions on which should not be illustrated, please post. Thanks!