I wanted to print something for my wife for valentines day. I liked the rose petals from XYZWorkshop (http://www.thingiverse.com/thing:152642), but wanted a better stem than a 3mm filament. I designed two different stems, one with and one without thorns.

The attached oscad script lets you select number of thorns and angle, then evenly spaces them vertically and radially around the stem.

Note: The rose petal STL is from thing 152642 (see above). I.e. not my design.

Printed at standard setting in makerware on a Replicator 2. Note, thorn angle likely has to be >=45 to avoid overhang problems, but YMMV depending on the printer.

I used a drop of superglue to connect the stem and flower.