How to create triangle/jagged edges on a cylinder (e.g. for a lamp shade) I'm looking for a good practice method of creating a triangle/jagged cylinder. My intention is to create a lamp shade with this zig-zag edges like the following. Basic stuff but I don't get it done.

example image http://www.shapes.info/s/cc_images/teaserbox_2450143432.png?t=1421415920

So, I played around with circles and paths in combination with the (array) modifier(s) but didn't accomplish the desired result. I tried with the modifiers because I like the handy way to adjust the outcome. 

TIA.
This is pretty straight forward. The advantage of this technique is it keeps the crease depth equal from top to bottom, just like a real world lamp shade.




Create a cylinder. Choose No Caps, and set the subdivision to 64.
Scale the cylinder on the Z axis (S+Z) to get the correct height.
Tab into Edit mode, switch selection mode to Edges
Select one vertical edge, then in the Select menu choose Select Similar>Length to select all the vertical edges
Select Checker Deselect in the Select menu to deselect every other edge
Click S+SHIFT+Z to scale the selected edges in towards the centre of the cylinder
Tab into Object Mode and add the Simple Deform modifier
Adjust the Deform Factor to a negative value to get a narrow top and wide bottom for the lampshade.