Decided to make a simple but solid seesaw for the kids. First I moved the kids sand box to create a suitable space for the seesaw (at least 10x4ft in area). I then built a simple frame using 4x4's and my spare pipe. Cross beam is 12". Frame height was about 35". I cut the pipe in the end to be about 24". Next trick was to attach the pipe clamps to the seat board. I needed more strength than just wood screws so I used short bolts. 1/4 bolts fit the clamps and were very secure. I probably could have got away with just two clamps. I drilled an insert so that the munchkins would not be walking on or bumping into exposed nuts. I dug holes about 12" in depth to place the frame. I aimed for the pipe to be approximately 22" off the ground. Once level all around I then used quick set post cement to lock it in place. I tried to keep the kids off for at least 20 minutes. I then drilled holes through the pipe on each side of each frame to place the locking clips (4 in total). A side benefit is that the seat board can be removed easily at any time for repair or events. You can also drill lower holes in the frame assembly for even smaller kids. My two just turned 4. Overall the seesaw turned out a lot more solid than I expected. 

I used parts I had kicking around:

• 4x4x8' post or I used 3@4x4x3' of spare pallet wood
• Aproximate 24" of 1 1/2" pipe (not sure why I had this, I think it was fence or antenna post)
• 2 @ lynch pins
• 2 @ pin clips

Parts I bought ($32 worth at Lowes this time)

• $10 - 2x10x8' spruce for seat board. I refuse to use preserved wood for heavily contacted areas. I'll paint it a solid color later. I also plan to shape the seat.
• $3 - 3 @ 1 1/2" pipe clamp. Two would work with the bolts I used.
• $3 - 6 @ 1/4 1.5" Bolt, lock washer and nut.
• $6 - quick set post cement. This stuff works well, just add water and tap.
• $10 - set of play structure handles.

I moved the patio stones from under the pergola to the back to be used as a patio for the fireplace and Laavu. A laavu is a Finnish wood shelter often used by campers/hunters/hikers/fishermen etc. throughout Finland. Mine needed a more pronounced area. I am happy with the results. I used a cub yard of sand and lots of elbow grease. The pad is constructed to comfortably fit a couple of Algonquin chairs and lava, in addition to the fireplace. The second pad is for occasional brush burning.