ExploderWizard
Hero
The hardest part of trap design is balancing practicality (would the evil overlord really put a rolling boulder trap here) and fun (who cares!) in a way that enhances play without sacrificing verisimilitude. It's one of the reasons i like adding tricks and hazards into the mix so that it is not always about a intentionally designed trap. Sometimes magic just leaks into the world and that refreshing pool of water makes you grow and extra arm -- that tries to strangle you!
Good points!
Not everything that is a "trap" in game terms was deliberately constructed just to put the screws to whomever discovers it. I just got finished designing a small "dungeon" for use in my game. It isn't really a dungeon, it's the abandoned mill from the old Expert set. The PCs have been hired to scout it out and take care of any harmful pests by the new owner who wants to fix it up.
This isn't some lair or tomb and there aren't any intelligent creatures using it as a base, so standard traps wouldn't make sense here. It is an old building in poor repair though so there may be areas that are "trapped" by completely normal disrepair. Some sections of the floor upstairs are unstable. Enough weight on these spots can cause the floor to collapse dropping explorers 20' to the floor below. Rot happens.
There is a large framework & elevator contraption once used to move product from the storage area upstairs to the main work floor below. The contraption is largely intact but years of neglect means that fiddling with it could prove very painful- again a trap not engineered by anyone.
IMHO traps work best when they fit in with the rest of the surroundings.