I printed up a sample map for this event. I decided that we could more easily work together on filling up a dungeon, rather than drawing it.
I chose Dungeon #1 from Paratime Design as our dungeon de jour.
Matt had a friend over named Justin and all three of us sat at the kitchen table and got down to work. I spent a little time talking about the symbols on the map, the scale of the map, and a bit about Moldvay's "Stock the Dungeon" table. The boys seemed excited so we began to take turns choosing rooms and deciding what the contents should be.
Justin was extra excited and he chose room #27 and began to describe what he thought should happen there.
He explained that there were monsters, asleep, behind the pillars. Glowing orbs of some kind. He said that you would have to be very quiet to sneak across the room without waking them up.
Matt chose room #58. He said that this room is the exit from the dungeon (it is) and that the door to the room would be magically locked. He said that the key would be hidden somewhere else in the dungeon. He chose room #31. He said the key would be on a chain around the neck of an ogre in that room.
The ideas kept coming fast and furious after that. One great idea involved ghosts and a special lantern, but I'm keeping that one to myself just in case I want to use it.
At one point, the boys discovered that some rooms have statues in them and I mentioned the "Startling Statues" table from the Ready Ref sheets. We had great fun rolling dice and statting up the statues around the dungeon. Room #38 has eight statues that turned out to be quite "startling".
I have to say that these boys had a knack for threading chains of events together. At one point, your character would need to find about five different objects in order to slay a wolf that had a key to open a vital door. I don't know where they learned this (I'm thinking video games) but they were really putting a complicated and interesting dungeon together and I must say I was impressed.
In the end, it was quite a successful first attempt. I hope that I can work with Matt again to do some further dungeon design work. Maybe next time we'll draw maps!
 I'll have to do a post on it sometime. It's a couple hundred pages culled out of many, many different reference works.