Cut Plastic bottles in the shape of a flower like shown below
Make sure the size of flowers is concentric and the sides are flattened, I kept them under a mattress to flatten them.
Fix them one by one into a kitchen paper roll holder.
For finishing touches on top, add a few strips cut from the bottle.
The base would be the remaining part of the bottle filled with bottle caps/paper for giving the tree a good balance. I have painted the bottom parts green and left the top ones while for a show capped effect. The only decorations you can have are the light weight ones. I have used silver coloured gift wrapping paper cuts.