Sliceform Cone
Ready-made PDF here: http://test.geogebra.org/~mike/Sliceform9cm.pdf
Works best on two colors of card (two shades of green for a Christmas Tree)
Finished version should look like this:
https://www.pinterest.com/pin/517632550894188865/
Here's an alternative pop-up version!
http://www.craftster.org/forum/index.php?topic=282491.0
Reference: look for books on Sliceforms by John Sharp from your favorite bookshop