As a Boy Scout, I learned many things. Some I still find useful today, such as first aid, basic knots, and how to start a fire. Some, not so much--how to make a hobo stove out of a tin can, for instance. One skill that I found fascinating, although I was horrible at it, was lashing, the art of securing two things together. It truly is an art, and when done correctly, you can create almost anything.
Would you stand on a tower constructed solely from sticks and string, with nary a nail or screw in sight? I would if Gever Tulley made it. His lashing tutorial at Make covers the basic elements of lashing in a clear and straightforward manner. Tulley's confidence in the strength of his creations is apparent, as is his proficiency in the craft.
A few possibilities that come to mind are non-permanent garden structures or possibly a knots and lashing-themed birthday party for an adventure-loving child. However you use it, lashing is bound to be one of those skills that proves useful in any number of ways somewhere down the line.
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(Images: Make/Craig Couden)
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I taught this stuff at a BSA camp for 2 summers, and loved it. we'd build a 20' tall signal tower and a monkey bridge, and all the campers who worked on them would be so amazed at what they'd done and so proud. Rope is a crazy versatile material (Google "sailor's knots"), and has a surprising, muscular beauty when well executed.
I learned so many great things in scouts - to use a knife and ax the right way, to build a fire and cook a decent meal in the rain, to plan and pull off an awesome week long canoe trip. To be aware of my surroundings and confident in my resourcefulness - this was a huge thing for a wimpy bookish suburban kid. It got me across Europe & Asia with a backpack & the money in my shoe, and it got me into an artist's studio where I think about every day when I pick up a brush and face that blank canvas. Be prepared, yo!
I'm in awe!