Making a penny spiral without adhesive, that just plain looks awesome.
You can also use this tutorial to make spirals out of any other currency as well.
Remember: if your creation falls over, don't get mad, you'll just end up wrecking it even more.
Step 1: Start the Spiral.
Easy enough. Find a good place to start, that's a bit out of the way. Aquire a large amount of coins, and get started.
Once you have laid your first coin down, think to yourself, "Do I really have little enough of a life to start working on this?"
Step 2: Build Outward.
Now, build outward, because a stack of pennies isn't all too exciting unless it looks good.
I chose to use a hexagon, because of personal prefrence, but you can do whatever shape you want as long as you can have a focal point.
Step 3: Build Up, Or, If You're Not Satisfied, Keep Building Out.
You could start building up here, but what fun is that?
Step 4: Attatch Pennies to the Outer Ring.
Step 5: Start Building Up!
Start building up by rotating the image slowly. After a while, once you're satisfied with the spiral's height, take a picture then build a different one. Have fun.