trap, damage, and XP

[Master Witch]

Ok how do you make traps? The book gives some examples of finished product but other then a range of damage per round it really say nothing about what should be used for a trap. I think that it leaves too much to, “o it works because of magic”.
How do I set XP for a tarp at first (ext) level that goes off once vs. every round? How much damage should it do if it only goes off once instead of ever round? I get the idea that a trap in meant to be equal to a monster but monsters do things ever round not just once. I personally don’t like to have every trap just be an immobile monster waiting for some one to step were it can reach them so it can all of a sudden magically come to life and start fighting from its arrow slit.
The damage is a big thing for me I don’t want to kill my PCs but at the same time a monster that does 1d6 per round in five rounds can do 5 to 30 points of damage. A trap that does 1d6 in the one round its active can only do 1 to 6 points of damage. How is such a low damage from a triggered device equal to a monster of the same level?

 

[Zustiur]

I'm concerned about this also. None of the traps listed in DMG are simple. How do I make simple old fashioned traps and how much XP do they warrant?
examples:
single firing arrow traps
pit traps
shocking grasp on the door handle traps

 

[BeauNiddle]

The problem with one shot traps is they are nothing more than a 'You Suck!' moment. The players can't react in any meaningful way to what happened so it's just down to the dice roll (if any) to spot it. Furthmore the bad guys can't really build an encounter around the trap (all or nothing damage is tactically weak) so they are unlikely to be parts of a memorable encounter.

That said onto the question:

You want the xp for a 'creature' that is designed to distract and momentarily worry the PCs but which can be overcome in one lucky roll.

Sounds like a minion. Find a minion of the right level and it should give you a decent stat line for attack bonuses and damage output with a precalculated XP.