With two 2x4s, two rubber bands, and two hours, you can make a working, adult-size pogo stick.

A couple years ago I made a pretty hard-core metal pogo stick for school (see this instructable), but that project required welding, machining, and about $100 worth of materials.

My goal for this project was to make things as simple (and cheap) as possible: all the materials cost about $30 and everything took me less than 2 hours to build (while taking pictures, not counting a few iterations of re-design).

If you're looking for the perfect DIY Christmas gift for your sad, dejected friend who weeps every time they see the weight limit on a Walmart pogo stick, then look no further.

Step 1: Gather Your Materials

Tools

Saw
Drill

Materials

Two 8-ft 2x4s
Several 2-1/2 inch wood-screws
Four 3-1/2 inch lag screws
Two heavy-duty rubber bands ($10 each at McMaster Carr, or $15 each at Amazon)
- Alternatively, you could try surgical tubing, bicycle inner tubes, etc.

Step 2: Bottom

Use eight screws to assemble the bottom crosspiece.

Step 3: Middle

Use another eight screws to make the middle.

Step 4: Attach Brace

Use four toe-nailed screws and a 9-inch brace to attach the bottom and middle pieces together.

Step 5: Attach Post

Use six screws to attach the post.

Step 6: Check Plunger Fit

Cut the plunger and make sure it slides freely through the holes in the bottom and middle pieces.

Step 7: Attach Plunger Top

Use two lag screws to attach the plunger top (this piece needs a little extra support).

Step 8: Attach Handle

Use another two lag screws to attach the handle.

Step 9: Optional: Round the Plunger Top

Use a file, sandpaper, etc. to round the top of the plunger. This might prolong the life of your rubber bands.

Step 10: Attach the Rubber Bands

The main idea here is to

Loop one end of a rubber band around the bottom crosspiece
Stretch it over the top of the plunger
Loop again
Stretch again
...

How many passes you make depends on how heavy you are, how high you want to bounce, how long your rubber band is, and how good you are at stretching rubber bands.

I had pretty good luck with tying two rubber bands together, then making six passes (I weigh 175 pounds).

Step 11: Jump on It

Hop on and have some fun!

PS: While it shouldn't really have to be said, bounce at your own risk. The design seems pretty sturdy to me, but I'm sure you could find a way to hurt yourself with it.

And, as always, use a helmet. People who don't use helmets are idiots. I can't believe those people :)