I've begun building a couple obstacles to mess around with. So far I have a "skinny" (really about a foot wide) to a drop in. I just finished a teeter totter from scratch and figured I'd post the plans for how I made mine. It's a little steep, but I figure practicing on something steep will prepare for most other totters.

---2-foot tall, 9 foot long teeter totter---

Materials to cut:

-48" x 2" x 4" board (x2)= a side base
-28" x 2" x 4" board (x2)= b width-wise base
-24" x 2" x 6" board (x2)= c vertical brace
-9' x 2" x 9" board (x1)= d teetering plank
-1" x 30" thick walled iron pipe (x1) axle
-1.25" pipe strap (x4) axle mount
--varying lengths of 2" x 4" boards (used for angular bracing)



Directions:

Keep in mind this is what I did, the height can be adjusted to suit one's own skill level.
-Two c's were cut first, this is the cut that determines the height of the obstacle. I chose 2 feet.
-Next I cut two a's at four foot a piece. I figured this was enough base to offset the momentum of the swinging plank.
-Board c was joined by wood screws at the center of board a (see photo, dashed lines indicate overlap).
-When assembled, the vertical board should be on the inside of the box that forms the base.
-The cut for the two b-boards was determined by adding 3 inches (two 2x4's) to the length of the pipe I used as the axle.
-For the angled bracing I just took some scrap wood and slapped them in there. The measurements would probably vary between constructions.
-The pipe has threads which will take caps, so I did not include the threads in the length measurement. -The b-boards were then used to join the vertical bracings to one another, forming a box on the ground. -Next the straps were screwed onto the tops of the vertical braces. I used straps a quarter inch larger than the pipe to allow for rotation.
-The pipe was slid into the braces, and iron caps were put on the ends of the pipe to keep water out and to keep the pipe from slipping out of the straps.
-I found the center of the teeter-plank by finding the point where it balanced then staked one end to the ground so I could attach the straps from underneath without the plank slipping from the center.
-the plank slips around horizontally on the pivot point, so I'm going to use a U-connector on each side of the board to keep it from moving around. I'll probably just go to the hardware store and browse for something that will work.

If you have any questions, or would like clarification on any part of this, please ask. Pictures to come soon.

Also, does anybody know of any good websites with ideas for obstacles? I find IMBA's website hard to navigate, and haven't found anything interesting on there.