· If you look closer at the available pictures you will notice there's no seams, so...
· Stop trying to use a long strip of paper.
· Start thinking in polar coordinates.
· You will need two dodecagons.
· Forget the inner spiral, it shapes itself when you put all folds together.
Let me now if it was useful 
EDIT: Many people send me e-mails asking for instructions via this forum. But I don't open that mail account very often (once in a year or two) so you can write me directly to 
pabloyungblut@outlook.com for the instructions. Thank you.